When creating a query on a data connection object the following error can occur at the point of selecting the data connection from the list of available modules:
System.NullReferenceException: Object reference not set to an instance of an object.
at System.Convert.ToString(Object value, IFormatProvider provider)
at System.Windows.Forms.ListControl.GetItemText(Object item)
This has been identified as a known software issue and logged as Problem 5318. If you see this error please contact your local support provider to have your instance of it added to the problem record.
The issue only occurs if the "Include real database names" option is enabled in Query and Report Designer's options. Uncheck this box direct after launching the designer.