Got a new PC in October and it has worked OK until a few days ago. Switched it on in the morning, booted OK. Closed it down and tried to boot up later and got a message asking for the proper boot device. Windows 7 will not load. Checked the BIOS and on the first page which lists the SATA devices, the DVD drive was listed, but neither of my HDDs showed up. However, they both were showing on the boot page. Checked Boot order was OK, but would still not load. Stuck my Windows 7 (64) CD into the DVD drive, tried a repair but didn't find an operating system. Used the Command prompt option and was able to access both Disks, so they're both working OK, but still not listed on BIOS screen. Ran a Windows start-up repair and also a CHKDSK/F on the C: drive which both appeared to find problems with file allocation tables and fixed them, but still no sign of either HDD in the SATA list and will not boot. This is an ASUS P7H57D-V EVO mobo with a 640Gb WD C: drive and a 1TB WD secondary HDD. Both connected as 6 Gb SATA drives (IDE option). 4Gb memory I really don't know where to go from here and would welcome any suggestions. I have contacted the tech support of the vendor (online company), but they don't seem to have a clue so far, so any other ideas might help.