We had another client get hacked so we had to do an emergency restore. At the end I got the all too common message " The user could not be added to one or more databases".
The fix in this case was to use SSMS to drop the users from all GP databases and then to add them back. I know about the steps in KB 929601. Has there been any thoughts about beefing up the scripts behind Tools->Setup->System->User Access to make all the necessary corrections? I find it odd that only rarely does this occur and when it does happens with a client with many users it becomes quite time consuming.