I'm a newbie, I know this format sucks but I'm stuck with it for now. When I create an audio cd with wma and mp3 files it plays all the songs on my headunit, but when I create a data cd my wma files won't play on my headunit "copy protected error", but my mp3 files are recognized and played. I have a valid license for all my wma songs. I'm using WMP 10 to burn my cd's. I also have Nero Burning Rom 6.2 and the same thing occurs. What if anything am I doing wrong.

Your computer has a valid license for your wma songs. When you put them on a cd and put it in the head unit, the license doesn't come along with them. I don't think that any cd-mp3 players like head units or walkman style players can play protected wma files. Portables can only do it because they have re-writable storage (the key can be erased when the license is gone).