Re: serialize a graphicspath
You can use BinaryFormatter and adapter class derived from SerializableAdapter class to workaround that. Have a look at the second post from the last for an example on how to do this.
In short, you can write your own data container for the information you need to be serialize from graphicsPath (you'd probably only need the point array and pathtype array) and have this class container marked as serializable, you don't need to save the entire graphicspath class since it would be a waste.
Re: serialize a graphicspath
Is this the same problem as the thread deserialisation problem or have you solved serialisation and omnly need deserializing now. In both cases post your code or better the needed part as a small demoproject so I see your needs and can help you