Firefox 7 freezes every 10 or 15 minutes on my Macbook Pro OS X 10.6.8, most often when I click the "back" button to go back one page. The Mac spinning, rainbow colored icon appears and Firefox ceases all functions. It will stay inoperative for five minutes or more, so I always "force quit" immediately and then restart the program. This has been happening for six weeks or more... I expected an update to correct this but one has not been issued.