At one point I opened FF and the browser window stopped taking up full screen. The program actually fills the screen, but the actual browser window has some sort of right hand margin. Right clicking in right margin produces no pop up menu. Browser currently looks as such http://i.imgur.com/8pgtE.jpg. I've tried closing, force closing, and restart of PC and does not revert back to normal. No plug in installed, however cannot be certain one did not update, although I believe none did.