VirusScan "Bad" DATS and Rolling Back
Occasionally McAfee issues a DAT file which has not been thorougly tested enough and leads to so-called "false positives" ie a legitimate file or files is detected (wrongly) as a threat... The most recent date on which this occured was on the 21st April 2010. On this occasion the main systems affected were Windows XP and McAfee 8.7i installations. However it could be any system and any version. Most anti-virus vendors occasionally issue anti-virus updates which give false positives.
The easiest way to deal with this kind of problem if the problem is not severe is to rollback to the previous DAT (ie the last good DAT). In general this can be done by going to the VirusScan Console>Tools>Rollback DATs and answering Yes when you are asked Are you sure you want to Rollback DATS?.
Or if you have rebooted after installing the DAT and have restore points on, you can revert to the last restore point before the most recent DAT.
In both cases you should temporarily disable your AutoUpdate task by highlighting the AutoUpdate task in the VirusScan Console. Then right-click on AutoUpdate and choose Properties. Then choose Schedule and untick Enabled Scheduled task runs at specified time.
Only re-enable Autoupdate after you have been told it is safe to do so.