Some problems with Firefox are caused by extensions, themes or hardware acceleration. This article will help you determine whether one of these is causing your problem and, if it is, describe how to make Firefox run normally again. https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems?esab=a&s=firefox+persona+themes+not+fit&r=1&as=s Note that you need an allow exception to make hover work. Tools -> Options -> Security : "Warn me when sites try to install add-ons": Exceptions You can check the HTTP response headers with the Live Http Headers extension to see if there are problems with retrieving the images. Live Http Headers: https://addons.mozilla.org/firefox/addon/live-http-headers/