Welcome back ajspurs
First step would be to find out if there are any application log entries after your computer restarts.
To find this out, make it restart, when it gets back into windows, right click on My Computer and select Manage.
This will bring up Computer Management, where you can select Event Viewer under System Tools. This will give you 3 sets of logs. Application, Security and System.
Check both Application and System for big red Xs around the time that your computer restarted.