User had copied or created a file / folder on a mapped drive and that file / folder now cannot be renamed / deleted / accessed by anyone. Not even administrators, upon the server.
An overnight Backup Exec backup had failed to access this folder also. I therefore needed this fixed.
Microsoft's offered solutions ( http://support.microsoft.com/?kbid=320081 ) did not help.
Viewing 'Open Files' in Computer Management application showed a user still had the parent and this directory open. I checked with the user and they had not so, I simply forced a 'Close Open File' in Computer management and then I was able to successfully delete the folder.
