Reset the page zoom on websites that look wrong: "View > Zoom > Reset" (Ctrl + 0 (zero))<br /> See http://kb.mozillazine.org/Zoom_text_of_web_pages If you increased the minimum font size then try a lower setting (default is none) as a too high value can cause issues like you described. *Firefox > Preferences > Content : Fonts & Colors: Advanced > Minimum Font Size *Firefox > Preferences > Content : Fonts & Colors: Advanced > "Allow pages to choose their own fonts, instead of my selections above" You can also do a check for corrupted fonts and other font issues: * http://www.creativetechs.com/iq/garbled_fonts_troubleshooting_guide.html - CreativeTechs Tips: Garbled Fonts Troubleshooting Guide * http://www.thexlab.com/faqs/multipleappsquit.html - Font Book 2.0 Help: Checking for damaged fonts