If the 80 GB drive is IDE and not SATA, and so can't be swapped with the larger drive, try simply unplugging and reconnecting both ends of the IDE cable, to attempt to resolve a loose connection. Leave the other ends of all of the power and data cables connected exactly where they are on the motherboard as you only want to change one thing at a time. If the 80 GB drive is also SATA, try unplugging the power and SATA cables from both the 1 TB drive and the 80 GB drive and swapping them over, as both the power and SATA cables, as well as the corresponding SATA port on your motherboard, are already confirmed to be working with the 1 TB drive. Loose connection to the 80 HDD (either of the power or data cable) or something that could have an equivalent effect, such as a defective cable.There are only really two possibilities at this point: Such a low-level problem would have nothing to do with Windows itself. A recent catastrophic failure of the 80 GB drive or loose cable connection has caused the smaller hard drive to fail to appear anywhere in the system, including in the BIOS. The D, E, F and G drives are all partitions on the same 80 GB HDD.
