WMP not playing proteced files after re-store

I'm running XP and WMP 9. Had to re-install XP and all
applications, incl. WMP 9. I restored also my old "My
Music" files back to the system, including the license
file, but WMP does not play now the "protected" files. It
will play all other files fine.

I do not get an error message when trying to play
protected wma files, the player just doesn't play them.

Tried to fix it with the Personal License Migration
Service, but this just doubled each wma file in the
player.

Thanks for the help!
Richard