I have seen some troubles with MP3 CDs. If you are making this for a specific player (like a CD MP3 player in your car), I would suggest you review the specific settings recommended in that unit's manual, and not use Nero Express. Make sure you choose to create a normal data CD (ISO9660, I believe), and check all of the settings to make sure they are compatible with your player's preferences. Also make sure that your filenames and ID3 tags are useable on that player.