AGS version 4.2 problem

we are using Novell access governance 4.2 and facing problem with Novell access governance since yesterday.

Any clue why we facing this problem..

2012-02-13 06:45:11,012 ERROR [com.aveksa.UI] com.aveksa.gui.core.SessionParams.<init>(SessionPa rams.java:127) -
java.lang.NullPointerException
at com.aveksa.gui.objects.ObjectStore.getObjectID(Obj ectStore.java:4537)
at com.aveksa.gui.objects.ObjectStore.getUser(ObjectS tore.java:1876)
at com.aveksa.gui.objects.datacleanup.GuiDataCleanupI temsUtil.hasViewUserAttrChangesEntitlement(GuiData CleanupItemsUtil.java:23)
at com.aveksa.gui.menu.tabs.mainmenu.UsersNestedMenu$ UsersTab.isAllowed(UsersNestedMenu.java:47)
at com.aveksa.gui.menu.NestedMenu.getTabs(NestedMenu. java:58)
at com.aveksa.gui.menu.NestedMenu.isAllowed(NestedMen u.java:83)
at com.aveksa.gui.menu.tabs.TabItem.isAllowed_new(Tab Item.java:80)
at com.aveksa.gui.menu.MainMenuManager.<init>(MainMen uManager.java:24)
at com.aveksa.gui.core.SessionParams.<init>(SessionPa rams.java:125)
at com.aveksa.gui.core.SessionParams.loginSystem(Sess ionParams.java:186)
at com.aveksa.jsp.compile.WorkflowFormCompileServlet. doGet(WorkflowFormCompileServlet.java:50)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:803)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at com.aveksa.gui.core.filters.LoginFilter.doFilter(L oginFilter.java:49)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doF ilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationV alve.invoke(SecurityAssociationValve.java:179)
at org.jboss.web.tomcat.security.JaccContextValve.inv oke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionV alve.invoke(CachedConnectionValve.java:157)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:262)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run( JIoEndpoint.java:446)
at java.lang.Thread.run(Thread.java:619)