I simply cannot open firefox. When I click to open it the screen flashes white but nothing else happens, firefox does not open. I have tried the thing where you press shift and click it at the same time (safe mode?) but that did nothing, instead of a white flash a smaller, black window flashes on but immediately goes off. I have tried completely uninstalling firefox and all related files but nothing seems to help. Please can someone help, I have tried everything I can.