So for the past month of so I've had an issue where every so often, the screen of my PC goes black and the whole PC then reboots. Sometimes it will reboot like this several times in a short timeframe, sometimes it will run for a couple hours and then reboot. It doesn't seem to matter if im running any particular program, it crashes just about anywhere. I took it to Umart (who assembled it) and they returned it telling me there were no hardware problems and they updated BIOS which should fix it. Two days later, I'm having the same problem. I really don'y want to resort to using Umart again, last time they told me it would be finished in 2 days and it took two weeks for me to get my PC back, which was very frustrating. If I can fix it on my own I'd like to. Does anyone have any advice?