Could you check on whether you have any unrecognized extensions on the Add-ons page? Either:

• Command+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable the extensions on the right side (or if completely unknown, remove). Bear in mind that extensions are optional; none are included with Firefox.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Does that help you regain control of Firefox?

If the problem continues, do you use Kaspersky security software? Some versions have a feature named "Anti-Banner" that have been known to cause redirects to a GIF file. This is a different file, but it seems somewhat similar to that problem.

Update your Flash Player Version 18.0.0.160
https://www.adobe.com/products/flashplayer/distribution3.html

See if there are updates for your graphics drivers https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

http://www.clamxav.com/ free malware scanner for Mac OS X https://discussions.apple.com/docs/DOC-3291

When checking my add-ons I found this plug-in I did not recognize

OpenH264 Video Codec provided by Cisco Systems, Inc.

I could not find out how to delete it so I deactivated it and so far all is good.

thanks,

Rob

RecoilRob said

I just updated and suddenly when I try to log into some forums or webpages I see the page for a split second, then I see the box asking permission for Adobe Flash for a split second and then it redirects to a page with /asp/images/bg.png suffix and the page displays "Page not Found" I have tried trashing and reinstalling FF.