Welcome to the CH forums.
Your pc is restarting on error..
Right-click My Computer, and then click Properties.
Click the Advanced tab.
Under Startup and Recovery, click Settings to open the Startup and Recovery dialog box.
Clear the Automatically restart check box, and click OK the necessary number of times.
Restart your computer for the settings to take effect.
After this whenever your pc encounters a non-recoverable error condition you should get a blue screen with a Stop error message. Post the entire error message.
Good luck