Ok, so I am resurrecting this thread, because the same thing is happening to me once again. This time I have a little more info. Issue: a. Windows will fail to load (from a cold start) b. Windows will load if I let the system warm up for abit (just figured this out) c. no error messages in event viewer d. no error "beeps" at start up e. no visual ques to indiciate an issue (artifacting, physical dmg, etc) Background: The problem is this: from a cold start (only when the PC has been shut off for a few hours) will the PC fail to boot into windows. However, if I don't shut the PC off - everything works just fine. Last time I couldn't get into windows and thought windows loader was screwed up, or possibly some nasty piece of malware, so I put in another hard drive, full format, and reinstall - worked great for the last couple of weeks or so .. bam shut the PC off last night cause it was ridiculously hot in here, and voila same issue when I woke up this morning and tried to get in to windows. I have tested the memory, seems to check out. No issues, but memory tests aren't always 100% This has happened on 2 different hard drives (what I had finally decided was the issue last time) so this is a fresh install, of a different version of windows 7 even, had been running fine. I have tried to call a couple of shops in town, but of course they aren't going to be of any help over the phone, they want me to bring it in so they can charge me 65$/hr to figure out the issue. So, I am really hoping someone can help me narrow this down please. All my fans seem to be working, there is no smell, or wierd sounds. I am thinking a couple of possible issue: 1 - It's the thermal creme on the cpu + heatsink, it's wearing out and causing an issue possibly (hence when it warms up and gets a little more liquid it makes that connection and it works. 2 - motherboard issue - though I have no idea why it would work better warm than cold - so not 100% convinced on this 3 - PSU issue - not a cheap PSU, it's a 1000w Thermaltake, again, no smell, fans working, no noise I am at a loss, I have a considerable amount of experience with computers and I have never had this problem, so I have no idea what the issue is, any help would be appreciated it. Cheers.