Try to set the gfx.content.azure.enabled pref to false or if this didn't help disable Direct2D by setting the gfx.direct2d.disabled pref to true on the about:config page and leave hardware acceleration otherwise enabled. That way you still have the benefit from hardware acceleration, but may not suffer from rendering issues. You can also try to uninstall Windows update KB2670838 if you have this update. *http://support.microsoft.com/kb/2670838 ---- Try to disable hardware acceleration in Firefox. *Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thank you, i uninstall the update and now it's working. Thank you very much.