so i've had my costume built pc for a couple of years now but this morning it was working fine. but when i got home from work i tried powering it on by pressing the main power button it booted up but didnt load no windows logo, but then kind of shut down. my mouse light was on and the led around the power button was lit up. then it kind of went dead. i tried again, pressing teh button to power it on and it wouldnt boot up. it was completely flat line. i walked out of the room. had a wash and so, came back in and it was on. weird? is this a virus issue or overheat issue?. im kind of boggled. cause be fore it switched off/restarted it's self.