Same 4 tabs open when I bootup Firefox for Mac OS 10.7 (Lion) and I can't change them??
I'm try to get Firefox 6 back to a single tab/no tab, standard start view in a FIrefox mac window.
I have read through the help pages again and found the answer in tab preferences and a bit of lateral thinking from me. By moving the "user.js" file to the trash and Quit Firefox, then restart the Mac – seems to work.