This is happening on up to date installations and other computers which have been virus scanned. 

''kah5217 wrote:'' This is happening on up to date installations and other computers which have been virus scanned. It looks like you're using Firefox 13.0.1, which isn't by any means up-to-date. It's a very old version that contains numerous security vulnerabilities. * https://www.mozilla.org/security/known-vulnerabilities/firefox.html Since you haven't provided an example link where the problem occurs, I can't be sure, but you're probably seeing so-called “in-text advertising”. * https://en.wikipedia.org/wiki/In-text_advertising It looks like you already have [https://addons.mozilla.org/firefox/addon/adblock-plus/ Adblock Plus] installed, so you shouldn't be seeing any ads. Try subscribing to both Fanboy's List and Fanboy's Annoyances. * https://adblockplus.org/en/subscriptions If subscribing to those lists doesn't help either, then the ads may be inserted into pages by one or more add-ons you have installed in Firefox. * [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems|Troubleshoot extensions]]