If I have a problem I copy back the last image. I use Drive Image 2002 and it takes a full image of my C:, D: partitions and saves it to my second HDD. I too would recommend a third party backup/restore program. Resulting in not knowing if the latest windows.updates are applied.
that they don't really know where there system is at. I hate System Restore - I see so many people get into a complete mess, going from one restore point to another, to last known good configuration, etc. If you are having problems getting the scan at boot I suggest that you download RajZors avast! External Control Tool and run/set it up from their. This behaviour is not limited to avast, virtually every AV company when giving indtruction in removal of a virus, warn that in XP you will probably have to disable System Restore because it is protected (windows system, hidden, etc., tec.) and going to be back.