Question: Application error

I have been using MapleTA for some years and very occasionally a student wil do something which results in him/her not being able to login. On login an error message looking something like the one pasted below occurs. In every other respect and for all other users, TA is running fine. As an administrator, I cannot find a way of resetting this user account. I have used a workaround in the past of creating another user but this is unsatisfactory for large student numbers. Has anyone else experienced this issue? Is there a common cause? Is there a way to reset the student's account? We are currently using version 4.

Many thanks for your any help with this,

Ian

Application Error
An error has occurred while processing your request. Please contact your system administrator for technical support. A detailed description is provided below to help diagnose the problem.

Description: invalidate: Session already invalidated

java.lang.IllegalStateException: invalidate: Session already invalidated
 at org.apache.catalina.session.StandardSession.invalidate(StandardSession.java:1098)
 at org.apache.catalina.session.StandardSessionFacade.invalidate(StandardSessionFacade.java:150)
 at com.maplesoft.mapleta.session.struts.action.LoginAction.execute(LoginAction.java:142)
 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.doPost(ActionServlet.java:432)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
 at com.maplesoft.mapleta.utilities.web.filter.WebContextFilter.doFilter(WebContextFilter.java:34)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
 at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:738)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
 at com.maplesoft.mapleta.utilities.web.filter.UTF8Filter.doFilter(UTF8Filter.java:30)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875)
 at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
 at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
 at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
 at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
 at java.lang.Thread.run(Unknown Source)