DRM problem in WMP 12

I use windows 7 home premium in an OEM version and have WMP version
12.0.7600.16415
I used to be able to play my DRM protected files i WMP 12, but now I cannot.
When I try to play a DRM protected file I get a messagebox saying, that WMP
cannot find the file: If you are trying to play, burn og syncronize an
element found in your library it´s possible this element points to a file
that has been moved, renamed or deleted.
I can click close the box or click online help, and if I do so I´m send to a
page showing WMP error C00D1197. The suggestions listed don´t help me.
If I try to play my protected files in another player ex. winamp it works ok.
What can I do to enable playing my protected files again?
Best regards
René
Denmark