Insufficient data for meaningful answer. Having said that it's more than likely a screen driver or virtual device manager issue.
Please post the stop code at the very least.
Turn off the automatic reboot so you can actually see the error when it happens—chances are it will tell you enough about itself to let you troubleshoot further. To change the recovery settings to disable automatic rebooting:
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.
Report back the full stopcode.