Wrong file error

I recently added a toshiba 40gb hardrive to my mpc1000. Yesterday I made a beat and saved it to the hard drive. Later on that evening I went to load up the session and the MPC gave me a wrong file! message. WTF? Using the program I saved, I managed to peice the beat back together and resaved the new session. The following day it loaded up correctly, but then today when I tried to load it up again, I received the WRONG FILE message when attempting to load up the beat's session. Why is this happening? Has anyone else experienced this problem? I've also experienced other minor issues when loading samples off the new hard drive. What can I do?

Did you format it when you first installed it? And are you running the Akai or JJ OS?

Since this post I haven't experienced any more problems. I discovered the problem was being caused by the way I was saving my files. I created multiple folders on the drive, one for samples, one for drums, and one folder for my "Beats", and within this Beat folder I began saving multiple folders (each seperately containing a session, program, and samples). I guess the drive couldn't load the files because I had too many saved within one folder? Once I started saving each "Beat" within one folder, outside of the Beat folder I had created, the problems ceased. Thank God. I didn't want to go through the hassle of having to return the hardrive to an online dealer. But I still do notice when I create a folder with multiple folders within it, I sometimes have issues with loading files. I guess for anyone out there with a similar issue, try not to save too many folders within one folder.