It is probably a driver which has gone wrong. Get this program
http://download.cnet.com/BlueScreenV...-10965136.html and use it to analyse the minidump file mentioned in the error report. That will tell you which file is associated with the crash, and you can tell from that which driver it is and either re-install it or uninstall it.
You might need to boot into safe mode to use it if you can't start Windows at all at the moment.