Cause: All of a sudden, hard drives and floppies disappear from the list of devices, or you cannot boot because the BIOS declares that you have no hard drive!
Solution: The most common reason for this error is a bad or loosely connected cable or incorrect jumper settings on the device. Check all the cable connections to the device. Ensure that the data cable and the power cable are properly plugged in both to the device and to the motherboard. Next, check the jumper settings. If two disks are connected to a single port, make sure one is set to Master and the other to Slave. Also check the BIOS setup program and ensure that IDE controllers are enabled. Go to the Integrated Peripherals menu and confirm that the Primary and Secondary Channels are enabled. If you are not comfortable changing individual values, reset the settings using the “Load Fail-safe (or Factory) Defaults” option.