Could you try disabling graphics hardware acceleration? Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches. You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.). orange Firefox button ''or'' classic Tools menu > Options > Advanced On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"