Hello everyone. I have had this problem with firefox version 21.0 since I upgraded to it a couple of months ago. The problem is that in the history tab I can not select "Restore Previous Session", "Recently Closed Tabs" and "Recently Closed Windows". I was able to select these options in the previous version and I have the same version of firefox on my other computer and this problem doesn't exist. Assistance in solving this problem is much appreciated.