I was running into a cross-threading error. I had hoped that using delegates would solve the issue. but instead I have a different error now. 

[code]    Public Sub AddChat(ByVal ParamArray obj() As Object)
        Dim callback As New AddChatCallback(AddressOf AddChatImpl)

        If Me.InvokeRequired Then
            Me.Invoke(callback, obj)
        Else
            callback(obj)
        End If
    End Sub[/code]

Data is recieved in mysocket.vb class
Event Is raised which is picked up by a form which is a child of an mdi form.
that form calls addchat in my rtb class.

I get a TargetParameterCountException when it gets to Me.Invoke in the If statement.  Obj does have data.  Any idea's?

I made the code changes
[code]
    Public Sub AddChat(ByVal ParamArray obj() As Object)
        Dim callback As New AddChatCallback(AddressOf AddChatImpl)

        If Me.InvokeRequired Then
            Me.Invoke(callback, obj.syncroot)
        Else
            callback(obj)
        End If
    End Sub
[/code]

This seems to have fixed my problem. Any other comments would be appreciated.

Calling Invoke() on a ParamArray method is tricky.  Using SyncRoot isn't really what you want to do -- it's not intended for use that way.

Is AddChatImpl's parameter a ParamArray?  You can just change it to a regular array.