Updating pages using Internet Explorer 7 do not work

The edit page looks good in Internet Explorer 7, but when pressing "save & view" the changes do not show up. Doing the same in firefox works fine.

No info in xwiki.log or console indicating any problems. Same behaviour is observed on jetty/hsql, but with this console output:
15:26:07,437 ERROR P1-19 http://localhost:8080/xwiki/bin/view/Main/WebHome AbstractFlushingEventListener:performExecutions:299 - Could not synchronize database
state with session org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException (SQLStateConverter.java:91)
..
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:611)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:585)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:307)

Additional observation: switching from wysiwyg to wiki looses all content of the page. Console outputs this when switching:
20-08-2007 15:20:26 org.apache.tomcat.util.http.Parameters processParameters
WARNING: Parameters: Invalid chunk ignored.