If you have increased the minimum font size then try the default setting "none" in case the current setting is causing problems. *Firefox > Preferences > Content : Fonts & Colors > Advanced > Minimum Font Size (none) Make sure that you allow websites to choose their fonts. *Firefox > Preferences > Content : Fonts & Colors > Advanced > [X] "Allow pages to choose their own fonts, instead of my selections above" It is better not to increase the minimum font size, but use an extension to set the default page zoom to prevent issues with overlapping text. *Default FullZoom Level: https://addons.mozilla.org/firefox/addon/default-fullzoom-level/ ---- You can also do a check for corrupted and duplicate fonts and other font issues: *http://www.thexlab.com/faqs/multipleappsquit.html - Font Book 2.0 Help: Checking for damaged fonts *http://www.creativetechs.com/iq/garbled_fonts_troubleshooting_guide.html