popeye67 wrote: the virus or trojan normally infects your restore feature first so that it can always reinfect the computer,
Popeye,
I would like to correct you on the above statement.
System restore is simply a collection of snapshots of your system at different times, eg. when you install software or when new hardware is installed. It also sets a restore point periodically, and you can make a restore point anytime you wish.
If it takes a snapshot and you have a virus on your PC at the time, the snapshot will include a picture of the virus.
Scanning software can detect that the snapshot has a picture of the virus but cannot delete it from the picture.
A system restore point that contains a snapshot of a virus that is/was infecting your computer, is NOT a threat to your computer unless you carry out a system restore to that point. The snapshot of the virus cannot reinfect your computer unless you do a restore.
If you have removed the active virus from your PC and you are certain that it is clean and running OK then turning off System Restore dumps all the snapshots including the picture with the virus snap included.
If you had done a restore using any restore point after you had contracted the virus then you would have been putting the picture of the system (including the virus) back into action on your hard drive and so you would be just as contaminated as before you had removed the original virus.
The reason for keeping SR turned on, even knowing that it has at least one snapshot which includes the virus, is that if anything goes wrong whilst trying to remove the virus with SAS or other program and you end up with a dead computer, you do still have a restore point to try to get back to and when you do, you can start all over again removing the virus.
Better to have an infected backup than no backup at all.
dave