I recently installed Firefox 100 on Windows 7 Home Premium 64-bit (a major leap from previously installed Firefox 56). No major squawks initially, everything was more or less as expected, but then I started to notice anomalies in the designation of visited vs. unvisited links, and possibly with clearing of history in general (see my previous question at https://support.mozilla.org/en-US/questions/1376052, still unresolved). I'm now convinced something is definitely wrong with history clearing and/or session restores. One glaring example: Firefox 100 is '''''overriding''''' my choice to uncheck the "Open previous windows and tabs" box in Settings/General. The box will reset to checked after I close/relaunch Firefox, and indeed I've seen it become reset to checked in the ''same session'', without even closing the program! Moreover, after clearing the history prior to exiting Firefox (Shift-Ctrl-Delete, all history and data boxes checked) and then restarting Firefox, the most recently visited website will often (but not always) be restored. Remarkably, when this happens and I go to Menu/History, it shows (or ''claims'') that history is empty! I have tried opening About:config and setting browser.sessionstore.resume_from_crash to false, it has no effect. This is very peculiar and disturbing, thanks for any feedback/suggestions.