had/going thru similar thing. (Strange). I got frustrated and set the pc to the side for about 6 months. Got it out last night and re-inserted ram sticks.(I left them out when I became frustrated.) low and behold the thing booted up to windows fine!. Maybe it is a bad ram stick? It did start running the hard drive VERY FAST so I am at troubleshooting mode again. It all began with a newer pc, about 6 months old since refurb. I was cleaning it and when I removed the cowl over cpu and removed heatsink it took cpu with it. I spread thermal paste on cpu and followed directions for replacing it. No dice...beep codes and # codes. I assume it is the thermal paste not spread properly but have no idea why it waited 5-6 months b/4 it decided to boot again. BUT , now my hard drive is running wide open it seems so I am going to take cpu out again and do a to the letter application of thermal paste and hope that is the problem. It did run fine for about fifteen minutes then the infernal whining of the hard drive. I hope maybe some of this related to others posts, and now I am on a search to find where the small tube of thermal paste is:( Good luck my friends. (it's live and learn with these p.c.'s