I have had a similar problem on and off over the years. If it wasn't the exact problem it was i wasn't able to copy a song from one hard drive to another. This was my fix: I UNPLUGGED MY FIREWIRE ISIGHT CAMERA and the problem went away. It's weird and I don't know if it always will work for me, but it has so far. I just had the problem again - which brought me to the forum - and it worked. Originally, i had the iSight connect to the HD itself due to the lack of firewire ports, when i plugged it into the computer directly, the problem went away. But today it happened again, and I though, hmm, maybe... and it worked. So try doing anything close to that for your setup. AND SPREAD THE WORD. I'm afraid to think what glitches may happen now that Steve Jobs is gone.