Has anybody else had this problem or know of the solution? Both my desktop and laptop - I leave them on at night and every couple nights I find that the computer has restarted. I formatted my desktop about a week ago to get rid of viruses and extra crap. It has done this before though...
????

 

I suspect that you have auto update enabled with the option to automatically install updates and reboot the machine at 3:00am.

Other than that I would say something is causing your machine to blue screen and auto reboot. If that's the case disable the auto reboot so you can at-least see the blue screen.
Bring up the system properties (It's in the control panel, keyboard shortcut is WIN+Pause/Break). Go to the Advanced Tab, Startup and Recovery/Settings, Uncheck the "Automatically Restart" button.

But I bet its the auto update thing.

 

The auto restart was unchecked. The audo update thing - I just disabled it. Hopefully it will stop randomly restarting. Thanks for your help

 

the answer should be in your system event log. start>run>evntvwr<enter>