Passing a Dataset from .NET 1.1 Win App to .NET 3.5 Web Service

Question

I have a .NET 1.1 C# windows application that needs to pass an ADO.NET dataset object to a .NET 3.5 web service.
 
When I run it I get an unhandled XML Exception occuring in system.xml.dll. System Error.
 
I suspect that it is due to the difference in .NET frameworks between the windows app and the web service, but I could be mistaken.
 
Is anyone able to shed any light on this most horrible of problems?