I recently got the following warning from my ZA program:

anti-virus/anti-spyware scanning has been de-activated. This can occur if the system clock has been set forward or anti-virus/anti-spyware updates are disabled.
Click here to update now and re-activate scanning.

The first time I clicked to update, the AV/AS turned on for a few seconds, then deactivated again. Updating directly from the ZA site did not work any better.