Have you changed your theme with an add-on? If you have, then revert back to the classic theme and see if this fixes the issue. Start browser in safe mode and disable the add-on.

Hi Smurf, and thanks for the suggestions (yours is the only reply I got)!

Unfortunately, no, I haven't changed the theme at all, no add-ons.

Can you upload a picture to this thread?

Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Did some research. Try an update of your graphics driver: http://support.amd.com/en-us/download/desktop?os=Windows%207%20-%2064

I'm also having this issue. Tried all the solutions above and no joy. Any further suggestions. WIN 7 and FF Ver. 38.0.5

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

If you use a non standard windows theme or made other appearance changes then try to revert those changes and use a (different) standard theme or Windows wallpaper.

• Control Panel > Personalization > Theme & Window Color and Appearance