Hi. I have looked through some other articles here at TechSpot relating to non-detected hard drives but did not find this peculiar issue. After four months of running just fine,n suddenly the hard drive is not detected in the BIOS but sometimes the Windows logo comes up (it has to see the hard drive from somewhere!) but does not open the operating system. COMPUTER SPECS--all components were purchased four months ago: Motherboard: ASUS M2A-VM, a low to mid-range board DRAM 3 GB Ultra Dual-channel Power supply: Thermaltake TR2-R1 450-watt Processor: AMD Athlon 64 2GH Hard drive: Seagate Barracuda 320 GB 72 RPM (Nice!) TESTS: I tried a different power supply unit. I ran the Windows CD, pressed R, and it declared that no disk was found. I ran the Ultimate Boot Disk and it did not see the hard disk. I connected the hard disk to an MSI motherboard, ran the BIOS, and it detected the hard disk. I did not run Windows as I knew Microsoft would not see it as the original motherboard. BIOS: The BIOS on the ASUS computer does not have a listing or selection for PATA. It just has IDE (the DVD drive) and four SATA connections. The hard drive is not detected but it is on SATA connection #1. I suspect a failed hard drive which is surprising since it's a Seagate. I don't have another SATA hard disk to test that idea with. I haven't tried clearing the CMOS, either, but at this point, I'm not sure what good that would do. This is a friend's computer that I put together. No, she didn't back up her files. I always tell people to back up their files. Sigh. So, what do you think?