Start with http://www.google.com/search?hl=en&q=0xd1&btnG=Google+Search&aq=f&oq=
But first try cleaning up the machine. Watch how at http://reviews.cnet.com/4520-11319_7-6240575-1.html
After it's all nice and clean consider reviewing the usual causes of 0xd1 as well as sharing how you make sure it's not malware.
I have a compaq SR1130NX that's about 4 years old and for about the past month, it's been shutting down randomly and giving me a blue screen with an error message (which I'll give you the link to.)
What it's working with...
A Presonus Firebox (sound card)
Nvidia chaintech 6600 AGP (graphics)
1 GB of RAM
AMD 64 2100 processor
For some reason, about every 4-8 hours, it shuts down randomly and gives me THIS...
Any idea as to what is causing this?