Delete the files sessionstore.js and sessionstore.bak and any existing files sessionstore-##.js with a number in the left part of the name like sessionstore-1.js . ..... See http://kb.mozillazine.org/Session_Restore

You can (temporarily) set the pref browser.sessionstore.max_tabs_undo to 0 to clear the Recently Closed Tabs list. Use the Reset context menu item to re-enable Undo Closed Tabs with the default value if you want to re-use that feature. .................... You can clear "Recently Closed Windows" if you restore a window and open a blank tab (Ctrl T) and close all other tabs with a middle click. If you close the window with only that empty tab then that window is removed from the list. To avoid that make sure that you close all tabs before closing a window. Set the pref browser.tabs.closeWindowWithLastTab to false on the about:config page to prevent closing the last tab from closing the browser.

i have my privacy set as as PRIVATE for all browsing, yet when i go to 'history', the 'recently closed windows' always shows the content of the last 3 closed windows. the 'recently closed tabs' is blocked; why isn't the 'recently closed windows' blocked as well? how can i make it such that the 'recently closed windows' don't appear. thank you.

I'm hoping someone can answer Alan's question. I also would like to erase all history immediately. I don't want there to be any trace of what websites I was on to the average user who uses my computer after I'm done.