UWL Login/Logout problem

Hi

Our portal platform is running on EP 7.0/ SP11. we are using UWL in our portal.

The problem we are facing now was:

When user logins into the portal there are no tasks displaying in the UWL. (we are getting waiting for update, after that No items displayed messages).

User logoff from the portal and again login the portal, then uwl shows list of Tasks assigned to that user.

Is anyboday face similar issue?

Thanks

Prasad