While putting an order on for a customer, if you click the "Customer Details" Button, then "View Orders" so you can look at their past orders and then look at an order, then close down the window, if you click on the "Customer Details" button again from the new order screen it produces an error message.
Comment Imported - The customer details button in the screenshot provided is not part of the core Sage 200 product and will be part of a 3rd party add-on or customisation.