Win Media Player stopped playing mp3s

I had installed WMP11 but apparently there was a problem with the installation, and I couldn't get Rhapsody to work with my Palm Pilot. So when Normsoft (Pocket Tunes for Palm) suggested that I uninstall ver 11 and use 10, I did that. It still didn't work, so I re-installed WMP10. That fixed the problem with Pocket Tunes, but then I couldn't play streaming mp3's with Firefox, IE or Opera. If I download the files (rather than playing the streaming content), some mp3s work correctly but most play at 2x or 4x speed. If I play EMBEDDED mp3's using a Flash player, it works fine, and WMP will play wmv/wvx files with no problem. I re-installed ver 11, thinking that 10 was corrupted, but I still have the problem. Any ideas? Tnx,
steve