Firefox 4 will not open any previous session once I shut down. I can have say 5 tabs open, close firefox, and reopen it and the session was saved. If I have those same 5 tabs open and shut down, then turn on my computer the next day, I can click on firefox, it will highlight the icon, and the highlight will disappear after about 5 seconds, and then I have to click it again, and it will open a totally new session. How do I fix this?