I have a custom built PC that I've been having problems with. I finished it in September and it was working properly until January. I started having troubles when it would give me the "Windows did not start properly" error and then continue in a diagnostic/repair loop; I have refreshed Windows twice from that error. After that, Windows didn't update properly and proceeded to go through a boot loop. I did a clean reinstall of Windows 8.1 and last night I received the "Repairing Disc Errors, this could take over an hour" message. This was on the screen for a few seconds and then proceeded to go through the same diagnostic/repair loop as before. I refreshed Windows again and ran both a CHKDSK and a diagnostic program I downloaded from the Western Digital website. Neither reported any bad sectors on the hard drive, but I'm almost positive that this is the problem. The hard drive was used when I bought it (I know, I know, worst idea) so I'm planning on buying a new one today. Is there anything that I'm missing that could be the problem instead of the hard drive?