I too just encountered this problem and the replies helped, but no one ever posted exactly what you needed to do to fix this so I will:

Here's the new Confserv.vb:
============================
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Tcp
Imports Conference

Module ConfServer

    Sub Main()
        Dim chan As TcpChannel
        Dim props As IDictionary = New Hashtable
        Dim serverProv As BinaryServerFormatterSinkProvider = New BinaryServerFormatterSinkProvider
        Dim clientProv As BinaryClientFormatterSinkProvider = New BinaryClientFormatterSinkProvider

        Console.WriteLine("Server started")

        serverProv.TypeFilterLevel = System.Runtime.Serialization.Formatters.TypeFilter Level.Full

        props("port") = 8086

        chan = New TcpChannel(props, clientProv, serverProv)
        ChannelServices.RegisterChannel(chan)

        RemotingConfiguration.RegisterWellKnownServiceType ( _
            GetType(Conference.Conference), "MyConference.rem", WellKnownObjectMode.Singleton)

        Console.ReadLine()

    End Sub
End Module

And the new ConfClient.vb:
==========================
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Tcp


Module ConfClient
    Sub Main()

        Dim commands As String
        Dim port As Integer
        Dim props As IDictionary = New Hashtable
        Dim chan As TcpChannel
        Dim serverProv As BinaryServerFormatterSinkProvider = New BinaryServerFormatterSinkProvider
        Dim clientProv As BinaryClientFormatterSinkProvider = New BinaryClientFormatterSinkProvider

        commands = Microsoft.VisualBasic.Command

        If commands.Length = 0 Then
            props("port") = 8088
        Else
            props("port") = CInt(commands)
        End If

        serverProv.TypeFilterLevel = System.Runtime.Serialization.Formatters.TypeFilter Level.Full
        chan = New TcpChannel(props, clientProv, serverProv)

        ChannelServices.RegisterChannel(chan)

        Dim attendee As New ConfAttendee.ConfAttendee
        attendee.Run()

    End Sub
End Module