This is a VERY typical problem that i get with my X1, and at first i thought it was the FD until sometimes even when copying the file to the HD still says SONG ERROR, try for example obtaining a midi file called "Dreamer" by Ozzy Osborne and try getting it going on the Ketron! Even copying it to the HD didnt work, so i had to use the Kar2Mid utility even though it was already a midi file! That sorted the problem out anyway.....strange...