(that's an offshoot of http://drupal.org/node/112729 )

disknode/1/0/10 is not writeble. The directory will be created when needed.

This is a useless and confusing warning. Shown when uploading to a directory which doesn't yet exist, which means that every new user sees this frightening red message. Also shown in this scenario: http://drupal.org/node/190768