Windows shuts down after 2hrs 15 / 25 mins, which isn't long enough to run a full scan. Can I set scan to restart from the point it left off, rather than begin again?

Note! Shutdown problem has been around for some time (Blue screen error?). I just want to limp along until a family member has time to sort the machine out for me.

I originally thought the problem was the cat blocking the fan vents, but it happens even when she isn't around!