I have a multi user version of Internet Security suite, running on 2 machines under XP. It is version

This morning, on one machine the "your computer is at risk" warning is displayed and attempting to update the anti virus/anti spyware software produces a blue progress bar and the message "error". It is currently running Anti-virus signature DAT file version 1059860672.

The other machine shows no error messages. Using the update also produces an error message but then the update product shows a green progress bar. It has now updated to Anti-virus signature DAT file version: 1059891680.

Any suggestions on why one system is working and the other isn't?