I built my first PC. Everything was fine. After about 15 minutes of surfing online my cursor froze, the monitor went black and the comp shut down. I looked into the case and saw the DRAM light on. I pressed the power button and it would not come on so I shut off the power supply. After a few minutes of waiting I turned the power supply back on and pressed the power button on the case and everything was fine again. Windows loaded up and everything was good. Fifteen minutes later it happened again, I was online looking up photos for wallpaper on google and as I scrolled down the page froze and the comp went black. Ran windows memory diagnostics (everything checked out okay). I looked in the BIOS and the ram information is there, everything checks out. I even updated my bios and still the same problem. What could be the problem?