It does appear to be a bad keycode but I'm not sure how to properly create one. Here's the steps I ran, please let me know if I'm doing something wrong. 1) I run KeyWizard.exe from a copy of GYM on my PC's Harddrive. 2) I created just 20 files for a quick test. 3) When instructed I started SonicStage 4.3.01.14050 4) I import the files into SonicStage. While doing this for short test I noticed that SonicStage actually imports the first file twice so it had 21 files rather than just 20. I deleted the duplicate from the library. 5) I transfered the files to my NW-HD3 6) I removed the files from SonicStage's Library and closed SonicStage 7) I completed the wizard which created the decodeKeys.dat and encodeKeys.dat After completing the generation of the key files I deleted all files off my NW-HD3. And did the following to load the songs. 1) Create a new X:\OMGAUDIO directory 2) Created a 0 byte X:\OMGAUDIO4CNTINF.DAT file 3) Copied the full GYM folder including the keys DAT files onto the NW-HD3 into X:\GYM 4) Ran Winamp 5.35 and loaded a single MP3 via ml_sony onto my NW-HD3. At this point I was unable to listen to the MP3 off the NW-HD3 in Winamp and GYM gave an unable to read ULD file header error when started. If I copy an MP3 with ml_sony without having the GYM directory so I all have is a OMGAUDIO directory with a 0 byte 04CNTINF.DAT, Winamp will be able to play the MP3 after it is transfered to the NW-HD3; however GYM will still give the ULD error and I will get the Mismatch System File error. If I start with a complete empty device and transfer over the same MP3 with SonicStage, GYM will open and play the file without issue; however, ml_sony will properly display the file on the NW-HD3 but it will not play it back. Of course the file will play back fine through the physical player at this point. Any idea on what I'm doing wrong?