The blue screen of death (BSOD) is typically due to a problem with a driver or the computer's hardware. It's also possible for malware to interfere with proper computer operation.

You are able to run in safe mode (which is a very basic diagnostic environment) because whatever is causing the BSOD hasn't been loaded in safe mode. Sometimes going back to a previous restore point will help, but these kinds of system problems usually require the computer to be examined by a computer expert.