This isnt my p/c or anything, just a Firefox SS I found. I know what you mean about the TAB thing, oddly enough thats never happened to me but thats probably because I delete 'Getting started, Mosted Visted, and Lastest Heahlines' from the Bookmark Toolbar, aswell as under Bookmarks, so whether I right click a link and hit 'open in new tab' or just open new tab it always opens a blank page. If you had all your settings checked so that it clears your private data when you close firefox nothing should be stored about what you were viewing. Granted, I dont have FireFox mastered or anything, but I havent had problems with it, the browsers I'd be most concerned with would be Interet Explorer since they had that security vulneribility about a year ago, and Google Chrome with all the privacys issues it had at launch, but like you said it could be a mac/pc thing.

I *think*, if you delete the Bookmark for it on the Bookmark Toolbar, and under regular bookmarks when you open a tab it should be blank, and if that doesnt do it there should be an option some where