The accdr extension puts your Access application in Access "run-time" mode, that is, the end user is not able to see the built-in navigation tools in Access. You will need to provide a navigation mechanism inside the application yourself (for example, a launch form with links to forms \ tables with which you want users to interact).
The accdr extension hides objects from the user, but this does not prevent them from changing the file extension back to accdb and changing your \ objects code.
To completely βblockβ the application, you need to create an accde file. This prevents the user from opening the form in the design view and making changes.
The following two links provide additional information about file types and how to deploy your application:
Access 2007
2007