So, I just bought a new external hard drive today, a WD My Book Essential with 640 GB so that I could back up with Time Machine. I plugged it into the computer, which then asked me if I wanted to use it for TM, and I said yes, etc etc... everything seemed fine until the backup got to 3.65 GB large, where it failed. It gave me an error message saying, "Unable to complete backup. An error occurred while copying files to the backup volume." So I went into Disk Utility, tried repairing the disk (where it told me that the disk appeared to be OK), and erased it to try again. Once again, the backup failed at 3.65 GB. Does anybody know if this is a problem with my new hard drive, or is this something I can fix myself??