hello tiger1, the behaviour you've described is not caused by any firefox update but by adware/malware on your pc. so instead of downgarding which won't help with your issue please perform the folloing steps: # [[Reset Firefox – easily fix most problems|reset firefox]] (this wil keep your bookmarks and passwords) # afterwards go to firefox > addons > extensions and in case there are still extensions listed there, disable them. # finally run a full scan of your system with different security tools like the [http://www.malwarebytes.org/products/malwarebytes_free free version of malwarebytes] and [http://www.bleepingcomputer.com/download/adwcleaner/ adwcleaner] to make sure that adware isn't present in other places of your system as well. [[Troubleshoot Firefox issues caused by malware]]