Firefox 8.0.1 ALL the on-sceen buttons on ALL sites have disappeared. I'm not talking about the toolbar buttons, I'm talking about buttons like NEXT and BACK and CONTINUE and PAY and GO TO BASKET and CONTACT US that should appear in varous parts of the screenh. Sometimes they are still visable (and clickable) as text, but in other cases they have disappeared entirely, although a click symbol still appears if you can guess where they are and mouse over them.