|No, no, no! You do NOT need a BIOS update & do NOT need to reinstall Windows. More than likely, your system is overheating. Check the temp readings in the BIOS under the PC Health menu. When's the last time you opened the case & blew the dust out of it?|
Your power supply may also be the problem. Overheating or simply old & tired.
Another possibilty is that you installed a buggy driver or program & you have Windows configured auto-restart when there's a problem rather that displaying the error message. Turn off auto-restart.
There's also the possibilty of infection. When's the last time you did a thorough cleaning...dumped temp files, scanned for viruses/malware/spyware, defragged, etc?