"Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now" "Remove the Cookies" from sites that cause problems: Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems --- Check the image exceptions: Tools > Options > Content: Load Images: Exceptions - See Settings for web content, pop-ups, fonts, and languages

See also Fix problems that cause images to not show and http://kb.mozillazine.org/Images_or_animations_do_not_load

Hi, I find the Adblockplus to be the biggest offender here, if you're using ABP then it's most likely the offender. Follow these instructions:

-Go to a site where captchas aren't loading. -Click on the Firefox button top left of screen -Click 'Add ons' -Click 'Extensions' tab -Find your ABP extension -Click 'Options' in ABP window -Click 'Filter Preferences' -Click 'Custom Filters' -Then click on 'Ad blocking rules'

The rule thats blocking captcha is 'google.com^' just uncheck it and then reload a webpage where you would see a captcha