1. Start > Run... > "regedit'
   
2. HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Right-click Windows Live > Export
   
3. Save it anywhere you want
   
4. In the same window, Microsoft > Right click Windows Live > Delete
   
5. Now go to C:\Program Files\
   
6. Rename the Windows Live folder to something else (in case something goes wrong, don't wanna have no way to turn things back)
   

That should get rid of it... If you have problems installing the old Messenger or something, you should put the Windows Live back in place, and then double click (and confirm with Yes) on the file I told you to save earlier and that'll bring things back to normal.

Can't rename? If you're running on Vista, I'm guessing it's privilege issues. Uhm, if you have deleted what I said to, try installing an older WL app anyways. It might still work. And keep that export, just in case.

Try system restore to before you installed it? And wow to be honest, you have a unique case 0.0