I also found out that the mp3 codecs: l3codecp.acm and l3codeca.acm co-exist after I had installed WMP10 in a working XP. So they are both located in the system32 folder. EDIT: WMP10 removed the lameACM mp3codec (that I had as default rip-codec) and replaced it with his mp3codec. LameACM is still installed, but no longer working in WMP.