Make sure you have the newist Winblows media player 9.1 and then reburn them. It is a compression tool. also if you have a setting ticked to burn a lead in that could be messing with the player.

I havent done a WMA burn to see if it will work in my navi unit. But mp3's seem to work very good! It would be great if it would read dvd disc packed with mp3's But it wont. has to be the 700 meg cd-r media.