That's because of the things I've posted in that thread:
CookieRevised's reply to MSN sounds...
and
CookieRevised's reply to MSN sounds...
A registry fix will NOT work for everyone and can screw things up for other people. A registry fix for this will only work for individual people and higly depends on the OS, language, soundscheme's used, etc... Hence the registry fixes in that thread were removed!
Also, a registry fix can't fix the true problem, because it IS a bug in MSN Messenger itself! (again see my posts in that thread)