When I install a theme on firefox, any theme, then it cannot show normally many web sites. It shows them transparent. I can see the desktop behind the browser. The web site is loaded and then some pieces of it get transparent. It happens even on facebook. When there is no theme, everything is normal. I updated firefox to version 8, but nothing is changed. I even deleted my profile and erase any preference/setting and still when I installed a (different) theme, there was problem again. I have no idea what started the problem at first place, that was long ago. I have windows 7, firefox 8. Please, help ?