|This may be a place to start, though I don't say it's definitely the cause of your problem, test the RAM.|
"BCCode: 50" is often associated with bad RAM.
Most people use "Memtest86" to test it, doesn't matter if Windows won't start. You can create a bootable CD or floppy from the free download (obviously you'll need a working PC on which to create the bootable disc):
Download the "Pre-compiled bootable iso" and burn it to a blank CD-R using a burning application which can write iso files to cd. If you don't have such software, there's a free trial of "PowerISO 4.6" which will do the job here: