Mayrell

CCleaner Version: v5.31.6104 (64 bit) Thunderbird Version: 52.1.1 (32 bit) OS: Windows 10 (64 bit) How to reproduce: - Close Thunderbird (if open) - Backup your Thunderbird profile data from C:\Users\<Username>\AppData\Roaming\Thunderbird\Profiles to a secure location - Run latest CCleaner with "Last Download Location" checkbox enabled in Thunderbird application settings - Open Thunderbird What happens: - Thunderbird cannot access existing profile data and shows first startup wizard (no "broken profile files" info or anything) - Profile data is still there but somehow corrupted, Thunderbird still references correct profile folder but cannot "see" it for some reason - As soon as you overwrite profile data with your backup, everything works again Conclusion: The new "Last Download Location" setting somehow corrupts Thunderbird profile data. I checked with only this setting enabled, it is definitely the cause of the problem.