VIrtual XWiki not working due to NullPointer on first view of Virtual Wiki when it tries to saveLinks

When creating a Virtual XWiki as described here http://www.xwiki.org/xwiki/bin/view/AdminGuide/Virtualization I get a NullPointerException when trying to first view the Virtual XWiki.

com.xpn.xwiki.XWikiException: Error number 13012 in 3: Exception while saving links
Wrapped Exception: null
at com.xpn.xwiki.store.XWikiHibernateStore.saveLinks(XWikiHibernateStore.java:1491)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:305)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:100)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:94)

This is not the same "ignorable" exceptions as described earlier on the VIrtualization page (where the state is saved and it's just a problem of rendering the page) - as the Virtual XWiki's simply will not load due to the problem.

This problem does not occur with 1.0 Beta 6 - which I tried first in the Virtual Machine - worked 100% - logged in created content, different users different Wikis etc. I then dumped all Xwiki tables and users from MySQL and deleted the Xwiki.war from Tomcat WebApps Then I installed and configured 1.0 RC3 as per Virtualization page again and this produces this problem.

This appears to be similar to http://jira.xwiki.org/jira/browse/XWIKI-932 in which it was suggested removing the Xerces.jars from (Jetty) Web Container - doing this from %TOMCAT_HOME%\common\endorsed (replacing with ones from Xwiki) did not help

Full Stacktrace from logs

19:02:02,218 WARN http-8080-Processor25 RequestProcessor:processException:528 - Unhandled Exception thrown: class com.xpn.xwiki.XWikiException
19:02:02,234 ERROR http-8080-Processor25 [action]:invoke:253 - Servlet.service() for servlet action threw exception
com.xpn.xwiki.XWikiException: Error number 3201 in 3: Exception while saving document XWiki.XWikiPreferences
Wrapped Exception: Error number 13012 in 3: Exception while saving links
Wrapped Exception: null
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:314)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:100)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:94)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:895)
at com.xpn.xwiki.XWiki.getPrefsClass(XWiki.java:2301)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:351)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:330)
at com.xpn.xwiki.XWiki.getXWiki(XWiki.java:446)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:96)
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:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:118)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)

Wrapped Exception:

com.xpn.xwiki.XWikiException: Error number 13012 in 3: Exception while saving links
Wrapped Exception: null
at com.xpn.xwiki.store.XWikiHibernateStore.saveLinks(XWikiHibernateStore.java:1491)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:305)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:100)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:94)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:895)
at com.xpn.xwiki.XWiki.getPrefsClass(XWiki.java:2301)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:351)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:330)
at com.xpn.xwiki.XWiki.getXWiki(XWiki.java:446)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:96)
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:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:118)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)

Wrapped Exception:

java.lang.NullPointerException
at java.util.Hashtable.put(Hashtable.java:396)
at com.xpn.xwiki.XWikiContext.setDoc(XWikiContext.java:158)
at com.xpn.xwiki.store.XWikiHibernateStore.saveLinks(XWikiHibernateStore.java:1470)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:305)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:100)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:94)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:895)
at com.xpn.xwiki.XWiki.getPrefsClass(XWiki.java:2301)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:351)
at com.xpn.xwiki.XWiki.updateDatabase(XWiki.java:330)
at com.xpn.xwiki.XWiki.getXWiki(XWiki.java:446)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:96)
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:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:118)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)