I have a form that uses a code behind done in C#.  The forms contains a
textbox and I am hooking into the onbeforechange event to do some code
validation.

To get the correct source node I am running this code.
private IXMLDOMNode normalizeSource(DataDOMEvent e)
{
if(e.Parent.nodeType == DOMNodeType.NODE_ELEMENT && e.Source.nodeType ==
DOMNodeType.NODE_TEXT)
   return e.Parent;

if (e.Source.nodeType == DOMNodeType.NODE_ELEMENT || e.Source.nodeType ==
DOMNodeType.NODE_ATTRIBUTE
   return e.Source;

return null;
}

After this I perform some very simple validation which does not pertain the
my question.  The odd thing that is happening here is that if the user types
directly into the text box my validation code works as needed.   However, if
the user has something copied to the clip board and then paste it into the
text box I keep getting a System.NullReferenceException.  Yet I cannot find
the source of my problems.

Anyone have any ideas?  Thanks,

-mike