When I try to boot up my PC quite often - but not all the time - it shuts down. Some times it's immediately, some times the power supply fan has been going 10 seconds or somewhere in between. The lights are on and I have to hold the power button down until it has completely powered down. I may have to do this 6 or 7 times before it finally starts properly.
Has anyone any ideas what it might be. Its an oldish Athlon 800 on an Asus A7V motherboard.