Is the cursor a blinking flat cursor on the upper left, or a mouse cursor?
Next time you restart, you might try going through the bios and making sure your boot device is set correctly.
Any messages in the event viewer around the time you restart?
When you restart, the memory has not been cleaned out. Possibly something is hanging around and causing the problem. Also, some devices may be in a different state. Maybe removing any external devices you have might work. For example, I have an external OEM hard drive that cold boots fine, but will not work for restarts.