Hi Conrad,
Disabling System Restore (Windows Me/XP):-
Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may also back up the virus, worm, or Trojan on the computer.
Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.
Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.
To disable System Restore, right click your My Computer desktop icon, and select Properties, then the System Restore tab. Untick the box, to switch off System Restore. Don't forget to enable it again, once you have cleaned your machine.
The advantage of running the antivirus scan in Safe Mode is that, hopefully, the virus, worm or trojan won't have then been activated by starting Windows. Safe Mode only starts the bare minimum of system requirements to make the machine work, and many virii (as as Sandra put it), can't be removed once running.
Hopefully that makes some sense - come back to us if you're not sure.