Bump to #30. It is true.
If it still does not work, try making a new (albeit temporary) user with full admin rights. I have had occasions where the user gets mugged during an upgrade to media edition... IOW new users have proper sound, but old do not.
I don't know why, but if the new user has sound, then do a healthy backup of your old user (Docs, mail, bookmarks, favs, etc) Delete your old user (w/ files), restart, and recreate your user and move all your junk back in.
Once done, of course, delete the original temporary user as well.
Oops. Ping to #39