Comment 34 for bug 269441

Logging out and back in clears it on 16.04 64-bit. Until next time, of course. I only installed fresh today so I'll try to itemize potential actions to trigger this. I had:

Deleted files from a mounted samba share
Deleted local files with standard permissions (downloaded debs from Telegram.com, skype.com)
Deleted email attachments (.doc and .xls - encrypted, came from a windows user).

I'll monitor this and post back if there's anything useful to add.