.net remoting error windows shell namespace extension dll

[PhilJohnson]

I am using business objects that are built on top of Rockford Lhotka's CSLA
Business Object framework.

I have a simple windows application that uses the objects configured for
remoting and the app logs on without any problems.

I have now created a Windows Shell Namespace Extensions application in C#
using the Renameable example from

http://www.codeplex.com/namespaceextension

(recently moved from

http://www.gotdotnet.com/Community/...leGuid=08ccce00-b2ba-4bee-9c29-a18f3ad85a65).

When I try to call my remote objects to login from this dll, I get a
remoting error:

"The Type System.Xml.XmlDocument in Assembly System.Xml, Version=1.0.5000.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089 is not marked as
serializable."

My understanding is that my dll will be running in windows' Explorer.exe
process. Can anybody help me to find out if this is what is causing the
problem and if so how I can get around it?

Even just helping me to find a way of debugging the dll would be useful (I
currently need to build the application then click on the icon that appears
in the Other section of My Computer to run the compiled version and see my
changes running).

Any help would be really appreciated.

Thanks,

Phillip