User-Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 Build Identifier: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 I enabled full screen mode and then closed the browser before disabling it. Now when I open the browser, it is automatically in full screen mode, and I can not get it back to normal. If I try exiting full screen mode, it screws up the layout completely. Reproducible: Always Steps to Reproduce: 1. Open the browser 2. Switch to full screen mode 3. Close the browser 4. Re-open the browser Actual Results: Exact same thing.
Is your Issue reproducible in Safe-Mode? https://support.mozilla.com/en-US/kb/Safe+Mode
Can't confirm on Win XP. FF starts in fullscreen but F11 works fine. Doesn't restore window size as before going fullscreen, but at least leaves fullscreen mode.
Do you have hardware acceleration turned on?