http://support.mozilla.org/en-US/kb/firefox-no-longer-works-mac-os-x-10-5 It was like a shock.. I need to know when the next OS X version will be released because I don't want to upgrade twice. I also have to say that I found this news randomly. I booted from external device Snow Leopard where I installed Firefox, but when I booted again from Leopard, Firefox did not want to start. I don't know why some preferences are changed when I alternate to boot, in the past I also had some issue with Spotlight because of that.