The first thing to check is your encoding settings in Windows Media Player. Open Tools/Options, and click the Copy Music tab. Then make sure that "Protect Music" is unchecked. This will prevent your continuing creation of DRM-ed files that encounter license issues.

But that won't rescue your old files; they'll have to be re-ripped after you change the settings (you could also re-rip to MP3, if WMA gives you too many proglems). An alternative to re-ripping could be to try Tools/License Management and Restore your licenses for purchased music.

Anything that can't be recovered that way might have been downloaded from a P2P service after having been uploaded by someone who left "Protect Music" turned on. I recommend NEVER ripping to a DRM-ed format; situations such as this are becoming more and more common.

Good luck,
Eliot Van Buskirk
Technology Editor
MP3.com