The error occurs when the form loads, specifically when the Me.EmpNameTableAdapter.Fill(Me.SalesEmpNameds.EmpName) runs.
No, all comboboxes are filled by various different datatables. The example I gave here is a very simple one. Like I said before the data loads into the combobox without any hitch and since this is a First chance exception the debugger doesn't stop it and a Try Catch doesn't catch it. It's very strange.