Stuart,

>I have a table that does not allow duplicate records, if I try and enter a duplicate record how do I catch the error and error message?

There are a few ways to handle this. First of all, you can create a business rule that does the check for a duplicate before the data gets saved. That way, the exception never occurs. For details on implementing this approach, check out the MM .NET Dev Guide topic “Checking for Unique Values”.
Other than that, if you want to catch this exception, you an override your business object’s HandleException method and put code in this method that handles the exception and adds a broken rule to the business rule object.

Best Regards,