Here are the images that were supposed to be attached.

Well, that's not good!

Could you test in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions, hardware acceleration, and some other advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Do text labels display normally in Safe Mode?

Firefox 37.0.1 appears to have some display glitches with Windows themes added by WindowBlinds from Stardock. If you have that program, you might need to switch to a default Windows theme temporarily until that problem is worked out.

You can try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

You need to close and restart Firefox after toggling this setting.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes
• https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

Thank you very much, both of you, for your help! Unchecking the hardware acceleration box worked.