Disable your Skype Add-on in Firefox

We’ve noticed some unusual behavior on our Web servers lately: Firefox browsers requesting pages, especially the pop-up timer, over and over, at rates up to 10 requests per second. Even blocking affected users in Apache didn’t work — the requests continued even when we were returning 403 Forbidden errors.

Thanks to the cooperation of a handful of users, we narrowed it down to the Skype extension for Firefox. As it turns out, that extension is what the Mozilla folks politely call problematic, and the behavior we saw is listed there: “web pages may continually refresh or stop loading”.

Therefore, we recommend disabling or uninstalling the Skype Firefox extension. Since Skype automatically installs that extension, many of you may have it without being aware. You can disable or uninstall it via the “Add-ons” item in the “Tools” menu.

It’s not necessary to uninstall Skype. The only problem is the Firefox extension that comes with it. If you do require that extension, upgrading to the latest version of Skype, 4.x, may help; all of the affected users so far have been using Skype 3.x.