Do you have the adblock plus add-on installed? I found that the white space on the right in my browser is where an ad is supposed to sit.

No it is not an ad block problem. Running with add-ons disabled does nothing to solve the screen problem. It has something to do with the cache and cookies or history, I think, as it comes and goes, depending on if a restore last session is used. Sometimes clearing an hour's wroth of history works.

Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl+0 (zero); Cmd+0 on Mac)
• http://kb.mozillazine.org/Zoom_text_of_web_pages

If you have increased the minimum font size then try the default setting "none" as a high value can cause such issues.

• Tools > Options > Content : Fonts & Colors > Advanced > Minimum Font Size (none)

Make sure that you allow websites to choose their fonts.

• Tools > Options > Content : Fonts & Colors > Advanced > [X] "Allow pages to choose their own fonts, instead of my selections above"

Thanks, these settings were already in place. AOL now says clear cache, cookies and history... to solve, which worked. (I cleared cache and one hour of history.)