I think I've found another bug in Visual Studio.NET :-(

I've got some DataObject classes that return arrays of objects. These used to return collections (using the System.Collections.ObjectModel.Collection generic class). I updated them to return simple arrays as I thought that would be more efficient.

Turns out that while ASP.NET seems to work fine with this, the design experience in Visual Studio isn't so good. Clicking on the 'Refresh Schema' task on the ObjectDataSource control that references the data object method, causes a "The schema of type 'Class1[]' could not be retrieved. Operation is not valid due to the current state of the object" error to be displayed.