Virus Scan Shutting down laptop

[ArPaNET]

Okay I am trying to help a friend that lives a couple hours away with her computer, It is an Acer laptop, reasonably new, running XP SP2... she said when she runs a virus scan the scan gets to a certain point and shuts down the computer. no other times, just when she runs a virus scan.

I told her to download AVG and scan with that, and if it still shuts down then try Trend Micro... she said that still shuts it down...
she is away from her computer right now but when she gets home I would like to be able to tell her whats wrong...

I searched, and came up with a couple things such as: over heating, bios upgrade needed and possibly a virus.

I was wondering what you guys think it might be, and how to fix it. Ill try to get more details when she gets home.

Edit: okay it is an Acer 5050, I had her try the scan in safe mode, with no luck, installed a temp monitor, and that was reading just fine... the only thing I can think of is to try and upgrade the bios. I have read that these along with toshiba's have problems with the computer not really overheating but telling it is, so it shuts down...

any help would be great thanks