Got a small issue re Firefox

[gvstn]

5. localstore.rdf

I can't say this will work but it won't cause any harm. I had a problem long ago with maybe FF 3.x where FF wouldn't remember to open in a full screen window. I deleted localstore.rdf on the idea that it might be corrupt, and let it be automatically recreated upon starting FF. After that it remembered my setting. I would think something like showing the menu bar would be in the same category of settings and the configuration may be stored in that file too. Deleting it may be worth a try.

Close FF. Go to Start and type in %appdata% but don't hit <enter>. Roaming appears in the list of search results so click that. It puts you in the Application Data folder. Go to Mozilla folder then Firefox then Profiles then xxxx.default folder. Delete localstore.rdf (or rename it if you choose, so you could undo but it won't be necessary). Start FF. Set your menu bar to show. Reboot and see if it sticks.

http://kb.mozillazine.org/Corrupt_localstore.rdf