Created attachment 8523425 [details] Screenshot (39).png User Agent: Mozilla/5.0 (Windows NT 6.3; rv:33.0) Gecko/20100101 Firefox/33.0 Build ID: 20141106120505 Steps to reproduce: Occurs in any site almost randomly Actual results: The Firefox menu bar turns completely blue and have to hover mouse around to clear that. The whole window frame or layout of the Firefox window turns blue, Australis graphic card issue perhaps. not sure though. Expected results: The blue rendering of the Firefox window might have not occurred in the first place, Now the occurrence rate is quite often during 10-15 min after launch.
Try to disable the theme you're using.