Upgraded to 25.0 release about 2 weeks ago (on Mountain Lion). Yesterday noticed the app slowing down considerably (beach ball) and memory use shot up, closed the app and re-opened. Upon reopening FF took a while and then presented a list of most of installed extensions/plugins as incompatible, when I then verified release number FF showed 10.0.0. Overlaying it with release 25.0.1 works for 5-10 minutes, then the app freezes and upon restart reverts back to 10.0.0. Tried deleting it, overlaying it, nothing works and I am not sure what to try next and not even sure how a much older release installs itself.