I am running Firefox on a MacBook, OS 10.6.8. I had actually given up using it for a while because I had gotten tired of the frequent freezes, but need to use a plug-in that is only available on Firefox for academic work. The freezes happen unpredictably; it might work fine for an hour or so with multiple tabs/windows open, then suddenly hang when I try to switch between one tab and another, or it might hang when I wake the computer from sleep. I get the spinning rainbow wheel, and while occasionally if I wait for a few minutes it will come back to life, most times eventually I have to Force Quit. I have uninstalled and reinstalled and tried running it in SafeMode, without improvement.