It all started last week when I didn't use my PC for a few days... all the sudden my 640gb WD internal disappeared from Windows Vista 64... came to the conclusion maybe my HDD had failed, so this week I bought a new WD 1TB HDD internal, and a copy of Windows 7, formatted my existing Samsung 160gb, installed Windows 7-64 on it, but my 1TB drive won't show up in bios, windows, anything. I'm confused? When I also have the 1TB connected Windows 7 takes forever to load up on my comp. When I unplug it my PC works just fine. HELP? I've even swapped the 2 SATA cables I have and same problem. Both drives are powered, it will detect the 1TB right when I turn on the PC but then says 3rd master fail, and doesn't show up in BIOS if that makes sense?