This message can appear if you copy your agent file (PCAWIN.AGT) to a computer with an older version of PC Access. If the older version of PC Access does not understand the file format, it can't load the agent list. The only thing you can do is set up all your agent information again. If you copy your agent file to a computer with a newer version of PC Access, PC Access automatically updates the file to the new format if necessary.
If you get this error message while running an Accessory program (such as the Slide Show), you may have a version mismatch between PC Access and that Accessory. If this appears to be the problem, follow the instructions for an Internal Error.