Firefox showing black or blank screen on websites.

Firefox version 33 includes a new feature called Off Main Thread Compositing (OMTC) which is a faster way of loading webpages. This new feature can cause a black or blank screen on some systems when starting Firefox or after visiting some sites. Mozilla has released an updated version of Firefox that fixes the problem. If you can use Firefox, see Update Firefox to the latest version for update instructions. If you can't use Firefox, you can download and install the latest Firefox version from www.mozilla.org using Internet Explorer or another browser. Alternatively, you can follow the steps in the Mozilla Support article at this link: https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems#w_turn-off-hardware-acceleration