My second pc sometimes will not boot up, not even into post. It switches on, fans spin up, the hard drive light comes on and stays on as does the dvd writer light, although the dvd rom light goes off. I can reset, switch off and restart the machine and nothing more than the above. Most of the time it happily boots up but just occasionally it behave as above. Tonight I had it on for about one hour, did some work on it copying some files across, switched it off for 30mins or so and now it wont boot. I have checked and reseated all IDE cables, ram modules, video card, I have disconnected the dvd's and even the hard drive but still no success. I will probably turn it on tomorrow and it will be fine. Occasionally it will boot into post and throw up an error message about it having failed to post several times and to hit F2 to enter BIOS or F1 to load defaults then it reboots and sometimes boots into windows and sometimes not. I'm curious as to whats going on here, anyone with some suggestions?