Firefox, Plugins, Totally CORNfused

[Jim]

I have two FC8 X86_64 boxes running Firefox-2.0.0.12-i386.

Box 1
Has plugins, Flash, JRE, Mplayerplug-in in /usr/lib/mozilla/plugins.
If you do a 'about:plugins' in Firefox you can see the plugins listed.

Box 2
Has plugins, Flash, JRE, Mplayerplug-in in /usr/lib/mozilla,
But if I do a 'about:plugins' in firefox, no plugins are listed.
If I put plugins Flash, JRE in /usr/lib/firefox-2.0.0.12/plugins and 
then do a 'about:plugins' I then can see plugins listed in firefox.
How can I get the Mplayerplug-in in /usr/lib/firefox-2.0.0.12/plugins .

And Most of all , why isn't the plugins not being read from 
/usr/lib/mozilla/plugins in both Boxes ??

First one to figure this out gets my heart felt THANKS.