"The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem."

I would stop using CCleaner on Firefox data first, at least for testing. That error usually means Firefox cannot access the places.sqlite database that stores bookmarks/history, and cleanup/security tools can keep or damage that file. Close Firefox completely, open Task Manager and make sure no firefox.exe process is still running, then add the Firefox profile folder to your cleaner/security exclusions. After that start Firefox again without running CCleaner. If it still appears, check about:profiles and try the Troubleshoot Mode/Refresh path only after making a bookmark backup, because places.sqlite is the file you want to protect.