can you supply a link to a site that uses sound that used to work for you?
2) I have Mdv 2008 but I use Opera and not fox, however you may have a broken link or no link to your browser. Have you tried to download and install flashplayer
I suggest you use the tar gz file.
3) /usr/lib/mozilla/plugins maybe the area you should look for 2 files.
if not there flash no workee.