I have two possible solutions for you. 1) System Preferences --> Trackpad "More Gestures" Tab Change "Swipe between pages" to "Swipe with two or three fingers" Change "Swipe between full-screen apps" to "swipe left or right with four fingers" (more details ans solutions here: https://support.mozilla.org/en-US/questions/852880 ) 2) Please see http://kb.mozillazine.org/Firefox_:_FAQs_:_About:config_Entries#Mousewheel. In about:config Set '''mousewheel.horizscroll.withnokey.action''' to 0 Set '''mousewheel.horizscroll.withnokey.sysnumlines''' to true ---- Please let us know whether this resolves the problem. Thanks!

Note that only the mousewheel.horizscroll.*.action prefs are currently supported in Firefox 17+ versions. See: *https://wiki.mozilla.org/Gecko:Mouse_Wheel_Scrolling