You don't have to worry about losing 2TB internal HDD after upgrade to v4.0.4. This new firmware will update your bootloader also, and about ISO/MP3 that failed to play - it should be plays fine in new v4.0.4.
If anything happen after upgrade, such as failing/hang/corrupted, you can easily re-flashing firmware to recover your unit.
Just read carefully on how to upgrade manual, and post your result here, and if your ISO file or anything else fails to play, feel free to report to firmware v4.0.4 discussion at http://www.mede8erforum.com/index.php/topic,4798.0/topicseen.html
oops, forgot to mention, you can use either NO_HD_AUDIO or INC_HD_AUDIO.
Thanks A lot (the-osiris) I appreciate the quick response, I Installed the new firmware the (INC_HD_AUDIO) version, it installed perfectly with no glitches, all my files are visable and playable, well I checked quite a few of them:) I have 6tb of movies so it will take awhile:) A lot of nice changes, I feel as though I bought a new media tank, what a change from v2.02, nice very nice, they did a great job.
Now like many others I have to figure out how to create and get my Wall working, lots of reading, I'm glad I listened to you people before about putting each movie in it's own folder under a genere and the I used Tvixie to get the info and photos on the movies, so all my movies are set up that way with the photos and everything else the media tank needs, I'm hoping I don't need the YMAJ program to make the wall work and have to do all of my movies over again using that program, that would take forever.
Once again thanks for the help.