I guess my Time Machine went forward in time and gave itself an upgrade to a future version by giving itself the ability to backup to an Airport Disk. Kidding aside, this is a confusing little bug that I thought someone here might have some experience in solving. The situation is that I backed up my hard drive using TM on Friday by plugging an external drive into my Macbook. It's an unwieldy solution so I moved my backup drive back to the Airport Extreme and figured that I would just have to move my Macbook there when I needed to do a backup. I did not expect Time Machine to work in any fashion over the Airport connection with the external drive. Last night I turned on the external drive for an unrelated reason and left it running for a little while. When I went to my Macbook I was surprised to find that it was backing up to Time Machine over the wireless network! Great- Except it's a bug of some kind. It was backing up to the external disk but it wasn't backing up correctly. Instead, TM had mounted a diskimage of the backup destination on my desktop with the corresponding file in the root directory of my external drive. Moreover, it was backing up my entire volume again, disregarding the previous backup. So I cancelled the backup (as it would likely take a long time to do a backup and fill up my external drive with duplicate files) and decided to plug in the drive into my Macbook again. The drive was recognized as a TM drive but once again it mounted a disk image on my desktop, began to backup the entire drive rather than just the altered files, and created an archive in the root directory of the external drive. Anyone have a clue as to what is happening and how to correct this odd behavior?