Stop: 0xc0000005 is a very generic error and could be caused by most anything.
Try these first:
1. Open a command window and type "chkdsk c: /f /v /r" (without quotes) then hit <enter>. Answer the resulting message with a Y, then reboot. This'll take a while.
2. Download memtest86 ( http://www.memtest86.com/
), burn it to CD, boot it and run at least 3 complete cycles on each stick of RAM individually in each slot followed by pairs, alternating slots between tests (gonna take a LONG while).
Corrupted file system or failing drive, and failed RAM are the 2 most likely suspects.