User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:18.0) Gecko/20100101 Firefox/18.0 Build ID: 20130104151948 Steps to reproduce: Opened a page with the monitor rotated to portrait and then opened the sidebar to bookmarks on a Macbook running system 10.6.8. I usually use my monitor this way without problems. Actual results: Sometimes it's fine. Often the menu and the sidebar turn black. Sometimes the whole window turns black. Sometimes the window turns black, reappears in landscape orientation, and crashes the machine. The cursor still moves, but the computer is unresponsive. Expected results: It should have just worked as normal.
>Sometimes the window turns black, reappears in landscape orientation, and crashes >the machine. The cursor still moves, but the computer is unresponsive. That sounds like a graphic driver issue. Does it work better if you disable the hardware acceleration with the checkbox in preferences/advanced/general followed by a Firefox restart ?
I don't think I installed a graphics driver. I think I am just using the generic one that came with the system. I turned off the hardware acceleration and it seems to have cleared up the problem. Thanks.
As far as I know you always use the driver that comes with the system on OSX. That doesn't mean that there are no bugs in the drivers, my Mac mini always crashes on OSX shutdown because it's connected to a Samsung TV ! The OS crash reboots the system and that means that I can't shutdown OSX :-) Can you please post the graphic section from about:support here ? Please don't post the whole about:support and you have to enter about:support as URL in Firefox.
Have you had a chance to get your about:support information? Also have a detailed step by step would be nice so that the issue can be reproduced.