WSUS Server Cleanup Wizard not working proberly

Hi

I have this problem with the WSUS Server Cleanup Wizard, that it can't delete some of the computers (4 pcs) that we have that haven't contacted the for more than 30 days.

If I use the CleanStale utility, it can't detect and move the 4 pc's:

CleanStaleComputers.exe /days:30 /delete:no /prompt:no

If I alter the day number to 20, it finds a lot of other pc's and move em to Stale Group (but not the 4 above).

I can manually delete the pc's, but in a couple of weeks, I have the same problem with some of the pc's.

Can the database somehow be corrupted ?

Best Regards

Peter