Problem with some PC's on domain updating VPS

We have a problem on a network where certain PC’s are not updating the VPS automatically.

Error message below. It seems that it is Windows XP SP3 machines, although there is one Windows 7 machine also listed with the error. Other machines (including other XP SP3 machines!) are updating perfectly fine.

Error message: Function setifaceUpdatePackages() has failed. Return code is 0x20000006, dwRes is 20000006.

Any ideas on what the problem could be?

ADNM v4.8.995

Have you tried forcing the update from one of the clients?

Hi Mac, thanks for the reply. I have tried pushing it out from the server and also connecting to the client PC and running the Avast UI and updating from there, but no luck.

I did a complete reinstall of Avast on the users machine, but the problem remains.

I have been failing to update avasti 5 virus data base. What could be the problem?