Welcome to the CH forums.
Sounds like you are blue screening but not seeing the error message because you have auto restart set.
1. Right-click My Computer, and then click Properties.
2. Click the Advanced tab.
3. Under Startup and Recovery, click Settings to open the Startup and Recovery dialog box.
4. Clear the Automatically restart check box, and click OK the necessary number of times.
5. Restart your computer for the settings to take effect.
Now when you go to shut down and a fatal error occurs, you'll at least see it and it won't cause an automatic reboot. You still have to sort out what's causing the problem.
Good luck