Below are the steps to reproduce the issue.
1. load firefox (normal, not private window)
2. visit a website that you have never been to before - we are going to need a nice unique url for later
3. close firefox
4. load ccleaner
5. clean all the firefox parts - history, cache, cookies, etc
6. load firefox and check your history - all looks good - nothing listed - all history cleared.
7. close firefox
8. in windows go to %appdata%\Mozilla\Firefox\Profiles\<your_profile>
9. open the file "places.sqlite" in notepad, or some other text editor
10. search for the url that you visited - you should find it
Now, this is where it gets interesting
11. load firefox
12 check the history, (just to be sure that it is still empty)
13. use ctrl-shift-del to bring up the firefox delete history options
14. select all types of data and select "everything" from the time
15. click the "clear now" button
16 close firefox
repeat steps 8, 9 and 10 - you should see that the URL is still in the places.sqllite file.
My feeling is that ccleaner has removed the references to the sites in the history in firefox, so when you then tell firefox itself to delete the history, it doesn't see anything there to delete, but the references are still in the SQL Lite database file. At this point, no amount of CCleaning or firefox history deletion will ever remove those references in the places.sqllite file.
The only solution is to delete the places.sqllite file itself through the OS.
OS: Windows 10 - Anniversary Edition (fully patched)
Browser: Firefox 49.0.1
Ccleaner: 5.23
I hope this is clear, if not, let me know and I send send further details.
