Error generating xml document during serialization: Project speci

[Donovan Zimmerman]

I'm getting the above error in 1 solution/project for the following
code but the exact same code works fine in other projects. References
are the same. I also get xml serialization error from a web services
in this solution, but the exact same calls and code work in other
soutions. I compared the underlying sln, proj, etc, files, and they
appeared to match among working and this non working solution. Anybody
have any ideas?

Dim serializer As New
System.Xml.Serialization.XmlSerializer(GetType(Lic ensing.License))
Dim oMemStream As New IO.MemoryStream
Dim oLicense As New Licensing.License

Try
With oLicense
.UserID = "Test"
.StateID = "Test"
End With

serializer.Serialize(oMemStream, oLicense) <-- errors here
MsgBox(Convert.ToBase64String(oMemStream.GetBuffer ))
Catch ex As Exception
MsgBox(ex.Message)
End Try

Other info, the code is running in Groove 3.0 w/ .Net 1.1 and
Hotfix(KB836616) and errors on both W2k and XP for the erroring project..

I also have encryption code for the license that encypts the serilized xml.
Being more complex but very similar, this code runs fine, which doesn't make
sense.

I've tried going to a Stream and String writer but receive the same error.

Thanks!