Does this happen on multiple computers? Can you disable hardware acceleration as a first try. Then perform these steps: *Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options. *In the Firefox options window click the ''Advanced'' tab, then select "General". *In the settings list, you should find the ''Use hardware acceleration when available'' checkbox. Uncheck this checkbox. *Now, restart Firefox and see if the problems persist. Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles: * [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems]] * [[Upgrade your graphics drivers to use hardware acceleration and WebGL]]