This issue came up after a customer replaced an existing computer with a new updated one.
Nothing was changed in System Five. Just a new installation was done of Pervasive and System Five, and then linked to the existing dataset. After doing this, the customer was no longer able to open existing invoices, or create new invoices. They could go to new sale, and then select the clerk, customer and invoice type, but once they clicked OK, the screen went away, and no invoice was opened. The invoice was getting created though because we could see it if we showed recent invoices, but even there, we were unable to open them. We went to another computer and logged in using the user name and terminal that the other terminal was using and everything was fine there. So it seemed that System Five was not the problem.
Even though we had determined that the issue did not follow the terminal, we also checked that if we used a different terminal number on the problem computer, the problem also went away.