Try to disable hardware acceleration.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

@ cor - el : I just tried that and restarted firefox , but it didn ' t fix anything . I also uninstalled firefox completely earlier today , but that didn ' t help either . Also , this is happening with all types of punctuation - slashes , dashes , commas , apostrophies , dollar signs , etc . if that helps at all . Here ' s a screenshot of the Yahoo ! homepage with some examples . You can see the $ signs spaced before the numbers , commas out of place , and links pushed down to the next lines form where they would usually sit .

UPDATE: I disabled add-ons and re-enabled each one manually and found that the settings on one of them was causing the problem. Changed the settings, and now firefox is back to normal.

Can you tell us which extension has such a setting and caused it?