I don't like anything opening automatically when I start Firefox, so before Firefox 4 I set Firefox to open a blank page when it starts. I still had set a page I visit frequently as my home page, so I could get to that page quickly by pressing the home button. If I needed to close Firefox it was nice and easy to have the option to save my session and close (I've already searched and read another post and answer on how to restore this feature in about:config). I understand that Firefox 4 always saves your session and you can restore it from the history menu, but then I would have to remember if I had anything open and click menu/History/Restore Previous Session. Now in Firefox 4 I have left the home page set to about:home so if I had tabs open when I closed it I would see the Restore Previous Session "button" the next time I start it. However, when I close all windows and tabs before exiting Firefox, the Restore Previous Session "button" will be sometimes be there. If I click it, it will open a random tab or window that I visited the previous day, which was NOT the last tab/window that I had open. If I do have tabs open when I close it, it does correctly re-open them when using the Restore Previous Session button, it only does this if I do a clean exit (close all tabs/windows before close). I tried deleting the sessionstore.js and sessionstore.bak files from my Firefox appdata directory (there were no other sessionstore.* files). This is a clean install of Firefox 4, I didn't install on top of Firefox 3.6.xx. I uninstalled Firefox 3.6.xx before installing and made sure to delete any leftover files in my appdata, programdata and program files directories.