Do you have that problem when running in the Firefox SafeMode?
http://support.mozilla.com/en-US/kb/Safe+Mode
Don't select anything right now, just use "Continue in SafeMode."

If not, see this:
http://support.mozilla.com/en-US/kb/troubleshooting+extensions+and+theme...

thanks for the reply the-edmeis

the problem does still occur in safe mode. I read the links and it seems like a lot of work.

Do you have any gut feel of what it might be so I can start there?

thanks

Do you still see that shortcut key if you open the Bookmarks menu?

On Mac the menus are maintained by the OS and not by Firefox.

You can try to remove the Firefox plist file.

User > Library > Preferences > org.mozilla.firefox.plist

Hi Cor-el,

Yes - I do still have the shortcut if I open the bookmarks menu.

If I remove the FF plist, will that delete my settings for preferences?

thanks