Strange problem, sometimes the comp will not start. I cant enter bios, all that shows up on monitor is a blinking cursor and keyboard is inactive. No matter how many restarts it will not boot. If you wait from 5-48 hours it my boot up normally but it has a mind of its own. Its not a virus or worm and Windows is fully updated. This has been going on for months intermitently. Bios is updated and I've tried 2 brandspanking new hard drives. Could it be a ram issue? If not what else could it be?

Check you cpu cooler and especially the fan on it because with the error vanishing after some time it sounds very much like a heat problem to me. I had this many years ago with a pentium 133MHz. It booted but posted all sorts of strange errors and blue screens. It nearly drove me nuts until I found out the fan didn't work anymore by pure luck. Cost me weeks and who know how many new installations and the next day it worked again! It can also be the power supply getting too hot. Check it out and it's fan also!