Hi SoS,
When was the last time the computer had a software update? or, also a fresh re-install of Windows?
The blue screen is of course indicative of a serious issue that's caused a fault. It could be anything, software corruption, incompatibility issue, memory problems etc etc and due to the Windows registry becoming corrupted.
I'm guessing it's a home PC and so long as you have all your data backed up, I'd say do a fresh install of windows and then get all the latest OS updates as well.
Cheers, DtM! West London & Slough UK!