Did this just happen overnight?

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

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

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} A small dialog should appear. Click Start In Safe Mode (not Refresh). 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 websites. Are there any problems?

Then restart.

Did all of the above and there is no change. Been going on for several weeks. I use different web browser for AOL mail.

Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

Problems have been coming up with v49 and 50. You may want to think about going back a version.

Ran safe mode with network. AOL not working correctly with Firefox. Tried Google Chrome AOL displays screens correctly.

I've called for more help.

I found the following:

https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

I followed the instructions on Firefox refresh and now AOL is working correctly.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

Problem solved.