Server loses the skin and gives several errors (Must be re-started) if attempting use "Add a resource" link when logged out.

I reproduce this on both FF and IE (And it appears to be a server not a client issue). It is not 100% reproducible, but do it a few times and it will happen.

1) use left nav "add a learning resource" while logged out.
2) If you see the log-in- page log-in and attempt to finish, then log-out and do #1 again.

Eventually the skin will be lost, and the server will need to be restarted to re-loaf the skin. Several different errors are seen:

Error number 4001 in 4: Error while parsing velocity page /templates/xwikivars.vm Wrapped Exception: Invocation of method 'hasAccessLevel' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /templates/xwikivars.vm[3,24]

Error number 4001 in 4: Error while parsing velocity page /templates/xwikivars.vm
Wrapped Exception: Invocation of method 'hasAccessLevel' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /templates/xwikivars.vm[3,24]
com.xpn.xwiki.XWikiException: Error number 4001 in 4: Error while parsing velocity page /templates/xwikivars.vm
Wrapped Exception: Invocation of method 'hasAccessLevel' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /templates/xwikivars.vm[3,24]
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:160)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:598)
at sun.reflect.GeneratedMethodAccessor144.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:294)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:194)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:241)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:155)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:598)
at sun.reflect.GeneratedMethodAccessor144.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:294)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:194)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:241)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:155)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:108)
at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:51)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:263)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:397)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:184)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:216)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:184)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:276)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:536)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:179)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:73)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:182)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at com.sun.enterprise.web.VirtualServerPipeline.invoke(VirtualServerPipeline.java:120)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:939)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:137)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:536)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:939)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:239)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.invokeAdapter(ProcessorTask.java:667)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.processNonBlocked(ProcessorTask.java:574)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:844)
at com.sun.enterprise.web.connector.grizzly.ReadTask.executeProcessorTask(ReadTask.java:287)
at com.sun.enterprise.web.connector.grizzly.ReadTask.doTask(ReadTask.java:212)
at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:252)
at com.sun.enterprise.web.connector.grizzly.WorkerThread.run(WorkerThread.java:75)

Wrapped Exception:

java.lang.NullPointerException
at com.xpn.xwiki.api.XWiki.hasAccessLevel(XWiki.java:1375)
at sun.reflect.GeneratedMethodAccessor163.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:419)
at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:73)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:125)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:241)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:155)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:598)
at sun.reflect.GeneratedMethodAccessor144.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:294)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:194)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:241)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:155)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:598)
at sun.reflect.GeneratedMethodAccessor144.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:295)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:245)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:203)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:294)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:194)
at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:170)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:318)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:241)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:155)
at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1429)
at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:108)
at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:51)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:263)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:397)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:184)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:117)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:216)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:184)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:276)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:536)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:179)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:73)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:182)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at com.sun.enterprise.web.VirtualServerPipeline.invoke(VirtualServerPipeline.java:120)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:939)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:137)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:536)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:939)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:239)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.invokeAdapter(ProcessorTask.java:667)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.processNonBlocked(ProcessorTask.java:574)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:844)
at com.sun.enterprise.web.connector.grizzly.ReadTask.executeProcessorTask(ReadTask.java:287)
at com.sun.enterprise.web.connector.grizzly.ReadTask.doTask(ReadTask.java:212)
at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:252)
at com.sun.enterprise.web.connector.grizzly.WorkerThread.run(WorkerThread.java:75)

Error number 4001 in 4: Error while parsing velocity page /templates/htmlheader.vm Wrapped Exception: Invocation of method 'parseContent' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /templates/htmlheader.vm[13,16]

Error number 4001 in 4: Error while parsing velocity page /skins/curriki8/xwikivars.vm Wrapped Exception: Invocation of method 'hasAccessLevel' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /skins/curriki8/xwikivars.vm[3,24]
Error number 4001 in 4: Error while parsing velocity page /skins/curriki8/htmlheader.vm Wrapped Exception: Invocation of method 'parseContent' in class com.xpn.xwiki.api.XWiki threw exception java.lang.NullPointerException @ /skins/curriki8/htmlheader.vm[8,16]