You will have to revalidate your registration code if you receive this error when attempting to open a return.
To do this:
-Log in as ADMIN
-Click TOOLS at the top and select UTILITIES/SETUP ASSISTANT
-From the Utility window, click SETUP
-Click SETUP ASSISTANT
The first window will be the registration window. Simply enter your EFIN and REGISTRATION CODE and click on the VALIDATE button. This will resolve the error.