Avast Antivirus alert on iastor.sys messed up my laptop :-P

When I started my laptop (WinXP) after I got up Wendsday evening, I got an alert from Avast Antivirus (which is set to update the program and virus definitions automatically) that was a trojan warning on iastor.sys (I can’t remember the path to what system folder it was in).

I googled iastor.sys and found several pages saying that while it is a system file, it can harbor a trojan. Avast recommended moving it to the virus chest and so I selected that, thinking “If something important messes up, I’ll just run system restore”

Unfortunately, that was not the case. Next time I tried to start my laptop, about two seconds after the part where the green thingy is going across the bottom of the screen, it bluescreened (something my laptop has never done in the 3 years I’ve had it), immediately shut down, started up again, got “windows did not start normally” and no matter what I select, the same thing happens all over again.

Now my laptop is at the repair shop I like to go to when I have a problem and the matter should be resolved quickly and without costing me a lot.

So now my concern is what if this happens again? What if Avast get an alert on another system file at some point in the future? Do I have it moved to the chest and have to put my laptop in the shop again to get it working or do I “take no action” and risk some virus or trojan messing up my system?