I just bought a Pod XT from a second hand music store, but it seems to be in really good condition, and may be unused. I went through the registration process and it did not work on the first try but eventually I was able to do it. The issue was an incorrect serial number. The sticker on the bottom of the unit, and a barcode sticker on the outside of the box both had the same number, and this is the number I tried using the first 5 or 6 times, but the process kept failing with an error. I then went ahead and downloaded the drivers and Monkey and installed them. I then connected the Pod to the computer and ran Monkey. I tried registering again and it took me to the same web page that I was attempting to register on before, but this time I didn't have to type in the serial number because the serial number field was already filled in, and the number was different to the one I was originally entering. This time registration worked and I also updated it to version 3. I had a look at the serial number sticker on the bottom of the unit, and noticed that there was another sticker underneath it. I slowly peeled away part of the top sticker, and the sticker under it looked the same with a barcode and serial number, but this number was different to the first one I was trying to enter initially, and was the same number that was pre-filled on the web page I was just on, and this is the number that worked. So somehow, there was a sticker placed on the bottom of the unit, with the correct number, and then another sticker placed over it with a wrong number, and this wrong number was also on the barcode sticker on the outside of the box. (When the initial registration failed, I raised a ticket and gave them the number I was using that didn't work, and I got a reply saying the number was not in the Line 6 database. I've since told them that it's now all good, and closed the ticket). I've seen a few posts where people have had trouble registering their Line 6 stuff, so i'm just thinking if this happened to my unit, it must have also happened to others.