Firefox has changed a lot lately, and some bug still exist ....
- The problem is with the Firefox graphics,
- Two "modes exist: OpenGL and Direct3D ...
- By default, Firefox is set to 3D.
To access these settings:
- Type "about:config" in the address bar and press the Enter key
- Look for gfx.3d_video.enabled and layers.prefer-d3d9 and set them to "False"
- Look fot layers.prefer-opengl and set its value to "True"
- Close and restart Firefox.