This can sometimes happen when the Mac OS or DP4 is updated. To fix this problem follow these steps.

- In Mac OSX 10.2 "Jaguar":
1. Quit all applications
2. From the Finder's "File" menu, choose FIND.
3. Next to "file name contains", enter the word AUTH.
4. Before clicking SEARCH, click the "Add Criteria..." button, and choose VISIBILITY. Set Visibility to ALL.
5. Finally, click SEARCH
6. In your list of found items locate, "AUTH-Digital Performer 4. Drag this file to the TRASH, and empty the TRASH.
8. When you launch DP4 again, you should be prompted to enter your name and key code. *Be sure to have the DP4 Install CD inserted and on your desktop when you type in the key code.

- In Mac OSX 10.3 "Panther":
1. Quit all applications
2. From the Finder's "File" menu, choose FIND.
3. Next to "file name contains", enter the word AUTH.
4. Before clicking SEARCH, click the "plus" (+) button to add a new line of search criteria. Using the pop-ups provided, make this second line to "Visibility" and "Invisible items."
5. Finally, click SEARCH
6. In your list of found items locate, "AUTH-Digital Performer 4. Drag this file to the TRASH, and empty the TRASH.
8. When you launch DP4 again, you should be prompted to enter your name and key code. *Be sure to have the DP4 Install CD inserted and on your desktop when you type in the key code.