I just got my Sansa Clip 4GB and started adding mp3 files to the Music folder. I had barely dragged over 21 files (85.5 MB) and when I tried to add another file, I got a pop-up error message saying, “The selected files could not be copied. There is not enough free space on the device.” Not enough free space? It’s a 4GB player! Will someone tell me what I’m doing wrong, or is the device defective?