Hi, i recently upgraded My Desktop from 32 bit to 64 bit Windows 8 Pro.
Your Windows PC might have automatically rebooted itself which caused Computers to crash and freeze..The first step in troubleshooting is finding more specific error details. Finding out the error details will only provide the solution to it.
Several issues could be the reason for this problem. First, make sure your anti-virus is up-to-date. A virus sometimes will cause random file corruption issues causing system to crash. Another likely reason is a failing hard drive, so you should check it for errors. Finally, look for hardware conflicts in the Windows Device Manager, a driver issue might be responsible.