I asked this before. The problem has come back. "Firefox is operating strangely. I recently updated to 5.0. Now, I use FF with several add-ons, including Too Many Tabs. When I closed FF last night, there were 5 tabs, plus a total of 31 tabs in 7 TMT toolbars. I closed FF normally. When I ran FF this morning, it opened over 20 instances of Firefox. All of them except the 'main' one had a little orange 'Firefox' at the upper left, and no toolbars, and the main one opened with a New Tab only -- that is, the 5 tabs that I had were lost. I think that this is a FF 5 problem, as this happens every day, and I didn't have this problem before, but I don't remember when it started. I think it started when I updated to FF 5, which was recently. Now, when I had the problem before, there were a whole bunch of sessionstore-##.js files in my profile folder. I deleted them (leaving the sessionstore.js itself), and the problem was solved -- for a few days. Now it's happening again, FF5 opens with over twenty instances -- two or three more every day -- and loses the tabs it had when I last closed, but there is only the one sessionstore.js. I have read the file and it looks like it's OK, but I wouldn't really know. The fix before was to delete sessionstore.js and sessionstore.bak. Is there anything else?