Not able to open the Task in MWS after 7.1.3 upgrade

Hello ,
After 7.1.3 upgrade we are not able to open Tasks from MWS->TaskListManagement , we are getting below error in MWS log.But the same task details we are able to open it from processModel step.

2013-02-27 09:12:54 CET (Framework : INFO) [RID:3158] - Processing request [n6ylz8gi5yzx:Administrator] http://xxxxx.xx.xxxx.xxm:8585/meta/default/wm_xt_fabricfolder/0000005294 (GET)
2013-02-27 09:12:54 CET (jsf : INFO) [RID:3158] - [POP.007.0059] The value given is null: java.lang.IllegalArgumentException: [POP.007.0059] The value given is null
at com.webmethods.portal.framework.portletcontainer.portletapi.BasePortletURL.setParameter(BasePortletURL.java:164)
at com.webmethods.caf.faces.bean.task.BaseTaskInboxResultPageBean.openTask(BaseTaskInboxResultPageBean.java:48)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:126)
at com.webmethods.caf.faces.application.CAFMethodBinding.invoke(CAFMethodBinding.java:67)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:72)
at javax.faces.component.UICommand.broadcast(UICommand.java:312)
at com.webmethods.caf.faces.component.table.html.DataTable.broadcast(DataTable.java:725)
at com.webmethods.caf.faces.component.ViewRoot.broadcastEvents(ViewRoot.java:202)
at com.webmethods.caf.faces.component.ViewRoot.processApplication(ViewRoot.java:116)
at com.webmethods.caf.faces.portlet.PortletLifecycle$InvokeApplicationPhase.execute(PortletLifecycle.java:670)
at com.webmethods.caf.faces.portlet.PortletLifecycle.phase(PortletLifecycle.java:250)
at com.webmethods.caf.faces.portlet.PortletLifecycle.execute(PortletLifecycle.java:145)
at com.webmethods.caf.faces.portlet.FacesPortlet.processAction(FacesPortlet.java:327)
at com.webmethods.portal.framework.portletcontainer.impl.PortletApplicationHandler.process(PortletApplicationHandler.java:477)
at com.webmethods.portal.framework.portletcontainer.servlet.PortletServlet.service(PortletServlet.java:58)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:473)
at org.mortbay.jetty.servlet.Dispatcher.dispatch(Dispatcher.java:286)
at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:171)
at com.webmethods.portal.framework.portletcontainer.PortletContainer.dispatch(PortletContainer.java:218)
at com.webmethods.portal.framework.portletcontainer.PortletContainer.process(PortletContainer.java:129)
at com.webmethods.portal.framework.portletcontainer.PortletContainer.processPortletAction(PortletContainer.java:107)
at com.webmethods.portal.framework.portlet.beans.rest.RestfulPCAHandler.handle(RestfulPCAHandler.java:182)
at com.webmethods.portal.framework.dispatch.DispatchManager.handle(DispatchManager.java:438)
at com.webmethods.portal.framework.dispatch.DispatchManager.handleDispatch(DispatchManager.java:371)
at com.webmethods.portal.framework.impl.PortalServlet.service(PortalServlet.java:249)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:428)
at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:830)
at com.webmethods.portal.framework.impl.NTLMFilter.doFilter(NTLMFilter.java:66)
at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
at com.webmethods.caf.faces.servlet.GZIPFilter.doFilter(GZIPFilter.java:32)
at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
at com.webmethods.portal.framework.impl.RequestFilter.doFilter(RequestFilter.java:56)
at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
at com.webmethods.caf.faces.servlet.XSSFilter.doFilter(XSSFilter.java:22)
at org.mortbay.jetty.servlet.WebApplicationHandler$CachedChain.doFilter(WebApplicationHandler.java:821)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:471)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:568)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1530)
at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:633)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1482)
at com.webmethods.portal.webApplication.WmWebAppContext.handle(WmWebAppContext.java:161)
at org.mortbay.http.HttpServer.service(HttpServer.java:909)
at org.mortbay.http.HttpConnection.service(HttpConnection.java:820)
at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:986)
at org.mortbay.http.HttpConnection.handle(HttpConnection.java:837)
at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:245)
at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:357)

It will be gr8 ,if some can help me to solve this issue.
Thanks in advance !!

Hari