one more thing, I checked the log viewer and found in warning :
15/12/2008 10:32 1229337133 SYSTEM 1128 Function setifaceUpdatePackages() has failed. Return code is 0x20000006, dwRes is 20000006.
15/12/2008 10:49 1229338167 SYSTEM 1128 Function setifaceUpdatePackages() has failed. Return code is 0x20000006, dwRes is 20000006.
I think the problem started after the today's update, because the database has been updated at 10:20 this morning.