Folder locked with MYSQL db, folder cannot be renamed or deleted

Server
1

Hi,
after my owncloud installation with a MySQL database I encountered the problem, that a folder (pictures) cannot be renamed or deleted any more. Any idea of what the reason could be? How can I resolve that issue?
I'm not very familiar with MySQL code.
Kind regards,
Thomas

2

Sorry, forgot to mention: It was a new installation of OwnCloud 10.0.2.