Error while Assign account to user

I had the following problem after upgrade CRM 3 to CRM 4:

Problem: general unexpected error while assigning account to user or to myself:

Solution: KB 948172  Error message when you delete a queue item from a queue in Microsoft Dynamics CRM 4.0: "Record is unavailable"

http://support.microsoft.com/default.aspx?scid=kb;EN-US;948172