My NoteTaker files (notebooks) are appearing as folders and won't open from the Finder, why?
OS X normally takes care of this itself. Each application tells the system what files types it can open, and what type are file packages rather than single files. For some reason either 1) the OS cannot get the info from NoteTaker because it is in a non-standard location, or 2) somehow, it's been manually or accidentally associated to another application with the .ntx file type on your system.
To fix this, select a NoteTaker document in the Finder, and select "Get Info" from the contextual menu. Open the "Open with:" section of the Info panel. Select "NoteTaker.app" from the menu. If it is not in the menu, select "Other..." and locate NoteTaker.app. Then click on "Change All...". This should resolve the issue and re-assign NoteTaker as the source application for opening your notebooks.