You need to disable the automatic reboot feature in the control panel. In the control panel go to the system folder, in the system folder under advanced there are the start up and recovery options, under system failure you want Write and even to system log and send an administrative alert selected and you want to un-select reboot the computer. Next you want to check your Event Viewer. Event viewer tutorial
. And post the last 4 errors in each category. Also if the computer happens to crash and you get a the blue screen of death (BSOD) write down the error code it gives you.
Systems and Network Engineer
Certified CompTia Network +, A +