Thought i'd start a new thread to address this issue that appeared in another thread. THE GOOD NEWS: I had your EXACT problem with the TC. THE BAD NEWS: The only solution was to replace it. Boooooo. I too am new to mac (well, new since my last 1993 Powerbook 540c back in 1994...which I still have by the way) and I converted back bigtime with a MBP, ACD, TC, Bluetooth MightyMouse and Keyboard. I have had problems with EVERYTHING and spent lots of time on the phone with Apple so i'm not impressed with the supposed "stable" system Apple boasts about, but I have found their support to be better than Dell... not saying much. My TC stopped connecting and mounting the drive but airport remained functional. Apple first said that the backup sparsebundle may have been corrupted, but even after erasing it, reformatting the TC and starting over, it still wouldn't connect. The only option was to replace the TC, which they sent it overnight and while I wasn't happy, it wasn't the end of the world. I don't know if your system is still functional even with the error message, but if so. Have Apple replace your TC, then obtain a backup, and then reformat the drive as they have suggested. I know its not the solution you wanted, but my TC has worked stellar ever since. Good Luck.