Getting error while working with jsr168 portlet in weblogic
portal 10.1

Hi,
I have configured jsr168 portlet to display RSS feed.I am not getting any  error
when I have logged in for 2 to 3 times. It's displaying fine.After that when I
again login I am getting this error.
I am not knowing what's the problem is?Let me know.

java.lang.NullPointerException at
com.bea.portlet.container.UserInfo.getAllProperties(UserInfo.java:149) at
com.bea.portlet.container.UserInfo.updateUserInfo(UserInfo.java:117) at
com.bea.portlet.container.AppContainer.invokeRender(AppContainer.java:704) at
com.bea.netuix.servlets.controls.content.JavaPortletContent.fireRender(JavaPortl
etContent.java:249) at
com.bea.netuix.servlets.controls.content.JavaPortletContent.renderInternal(JavaP
ortletContent.java:156) at
com.bea.netuix.servlets.controls.content.JavaPortletContent.beginRender(JavaPort
letContent.java:103) at
com.bea.netuix.servlets.controls.application.laf.ContentControlRenderer.beginRen
der(ContentControlRenderer.java:48) at
com.bea.netuix.nf.ControlLifecycle$7.visit(ControlLifecycle.java:481) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
18) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:220) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:395) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:361) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:352) at
com.bea.netuix.nf.Lifecycle.run(Lifecycle.java:326) at
com.bea.netuix.nf.UIControl.render(UIControl.java:582) at
com.bea.netuix.servlets.controls.PresentationContext.render(PresentationContext.
java:486) at
com.bea.netuix.servlets.util.RenderToolkit.renderChild(RenderToolkit.java:146)
at
com.bea.netuix.servlets.jsp.taglib.RenderChild.doStartTag(RenderChild.java:62)
at
jsp_servlet._framework._skeletons._pcagreen.__flowlayout._jspService(__flowlayou
t.java:290) at weblogic.servlet.jsp.JspBase.service(JspBase.java:34) at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226) at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124) at
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283) at
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175) at
weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherI
mpl.java:528) at
weblogic.servlet.internal.RequestDispatcherImpl.include(RequestDispatcherImpl.ja
va:454) at
com.bea.netuix.servlets.controls.application.laf.JspTools.renderJsp(JspTools.jav
a:130) at
com.bea.netuix.servlets.controls.application.laf.JspControlRenderer.beginRender(
JspControlRenderer.java:72) at
com.bea.netuix.servlets.controls.application.laf.PresentationControlRenderer.beg
inRender(PresentationControlRenderer.java:65) at
com.bea.netuix.nf.ControlLifecycle$7.visit(ControlLifecycle.java:481) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
18) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:220) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:395) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:361) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:352) at
com.bea.netuix.nf.Lifecycle.run(Lifecycle.java:326) at
com.bea.netuix.nf.UIControl.render(UIControl.java:582) at
com.bea.netuix.servlets.controls.PresentationContext.render(PresentationContext.
java:486) at
com.bea.netuix.servlets.util.RenderToolkit.renderChild(RenderToolkit.java:146)
at
com.bea.netuix.servlets.jsp.taglib.RenderChild.doStartTag(RenderChild.java:62)
at
jsp_servlet._framework._skeletons._pcagreen.__gridlayout._jspService(__gridlayou
t.java:292) at weblogic.servlet.jsp.JspBase.service(JspBase.java:34) at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226) at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124) at
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283) at
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175) at
weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherI
mpl.java:528) at
weblogic.servlet.internal.RequestDispatcherImpl.include(RequestDispatcherImpl.ja
va:454) at
com.bea.netuix.servlets.controls.application.laf.JspTools.renderJsp(JspTools.jav
a:130) at
com.bea.netuix.servlets.controls.application.laf.JspControlRenderer.beginRender(
JspControlRenderer.java:72) at
com.bea.netuix.servlets.controls.application.laf.PresentationControlRenderer.beg
inRender(PresentationControlRenderer.java:65) at
com.bea.netuix.nf.ControlLifecycle$7.visit(ControlLifecycle.java:481) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
18) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at
com.bea.netuix.nf.ControlTreeWalker.walkRecursiveRender(ControlTreeWalker.java:5
29) at com.bea.netuix.nf.ControlTreeWalker.walk(ControlTreeWalker.java:220) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:395) at
com.bea.netuix.nf.Lifecycle.processLifecycles(Lifecycle.java:361) at
com.bea.netuix.nf.Lifecycle.runOutbound(Lifecycle.java:208) at
com.bea.netuix.nf.Lifecycle.run(Lifecycle.java:162) at
com.bea.netuix.servlets.manager.UIServlet.runLifecycle(UIServlet.java:388) at
com.bea.netuix.servlets.manager.UIServlet.processControlTree(UIServlet.java:301)
at com.bea.netuix.servlets.manager.PortalServlet.service(PortalServlet.java:927)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) at
weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecuri
tyHelper.java:226) at
weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.ja
va:124) at
weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283) at
weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26) at
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42) at
com.documentum.web.servlet.CompressionFilter.doFilter(CompressionFilter.java:108
) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at com.documentum.web.env.WDKController.processRequest(WDKController.java:95) at
com.documentum.web.env.WDKController.doFilter(WDKController.java:83) at
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42) at
com.documentum.web.env.PortalRequestFilter.doFilter(PortalRequestFilter.java:92)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at
com.bea.p13n.servlets.PortalServletFilter.doFilter(PortalServletFilter.java:336)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at
com.bea.portal.tools.servlet.http.HttpContextFilter.doFilter(HttpContextFilter.j
ava:60) at
weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42) at
weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAp
pServletContext.java:3393) at
weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.ja
va:321) at weblogic.security.service.SecurityManager.runAs(Unknown Source) at
weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletConte
xt.java:2140) at
weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java
:2046) at
weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1366)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:200) at weblogic.work