Rolling reboot problem, computer reboots for know

Probably getting too hot or HDD problem.

If too hot you may take of the case and blow out the system with an air compressor (just take it outside away from clean things). Also while it is apart clear away any lint debis from the CPU fan & heatsink area. Leave the case off and hookup your system again. This will do two things, 1.) give you better airflow to test the heat theory and 2.) give you a chance to peek at the CPU fan to see if it is moving well. Depending on your motherboard you may have a sensor monitor in the bios which will allow you to check the tempature of the CPU as well as the fan speed.

If it is a Hard Drive problem listen for a noisy drive arm (clicking sound). Lastly if it's a memory problem you can tell by swaping out the chips. But i would lay odds that it's a heat issue. Hope this helps, Best Regards, -md