Certain viruses that infect the master boot record (MBR) or boot sector can cause the system to display a blue-screen. If you just see your computer rebooting before you get to the Windows logon screen then this could also be a blue-screen, but your computer is set to restart automatically on system failure. After this happens, you’ll often see Windows display a black screen with some boot-options available such as “Safe Mode”, “Safe Mode with Networking”, etc.. One of these options called “Disable automatic restart on system failure” will help you determine what the first steps are, as you’ll be able to take note of all the information displayed on the Blue-screen. Often these steps will provide hints with troubleshooting steps, and the error codes will give you some targeted things to Google search for solutions to this exact problem.
Unfortunately, some rootkits and mbr viruses leave trip wires, such as references to virus related files in the Windows\assembly folder. If these files aren’t detected by your anti-virus program as well, then they can cause blue screens. That’s why you should always make sure you have a couple of working system restore points to fall back to, before running any scanns.
If all removal attempts fail, there’s often no other choice than to reformat the entire HD, and start restoring the user files from a backup.