FF frequently fails to restore tabs losing all my previous work before I've finished. It's very annoying and frustrating. In search help the answer is not simple to understand. Please tell me, what is sessionstore and where can it be found? Why is there not a button to fix this problem? If sessionstore gets corrupted frequently as mine seems to (according to the answer) why not have a sessionstore back-up and a routine to correct the problem or at least easily recover from the corruption?