Scarlett1208,

Installation on the Xbox360 for the PlayOnline and FINAL FANTASY XI software is unlike anything else on the system, and as such can be corrupted if you do the file transfer from an old HDD to a new HDD. More than likely what has occurred is that there is still remnants of the original FINAL FANTASY XI installation on the new HDD, put there by the transfer, and it’s interfering with the installation.

What you will need to do, unfortunately, is wipe the HDD and start over. You will want to backup any profiles, save games, etc to an external source (such as a Memory Unit or a properly formatted USB Flash Drive) so you don’t lose that information, and then format the HDD. Once that is complete, you’ll be able to go through the full installation process without any problems.