I had a rather large Firefox session open - 6 windows with multiple tabs open in each - for quite a while. Any time either the browser or the computer would crash, session restore always reopened everything as it was, apart from the most recent one. It didn't even crash, rather the OS restarted after updating. When I opened FF as normal and went to session restore, only 5/6 of the windows were restored with it. I went to Library -> History -> Recently closed windows, and while it reopened the window that was missing, it only reopened it with the tab that was open at the time of the crash - all other tabs were missing. I tried a system restore to the previous day (and a few even earlier) but no joy. Is this window gone forever or is there some other way to resurrect it? Thanks!