InfoPath Dev

One of the users of a form I developed cannot run any of the VB .NET programming I've written into the form.  She has all the latest .NET Framework updates installed, including 3.5.  A good example of the problem is when she clicks a button where the programming determines the selected node of a repeating table, makes some calculations, and then populates some other fields with the results.   She gets the following error details:

 Request failed.
   at Microsoft.Office.InfoPath.MsxmlNavigator.IsValidNode(MsxmlNode test)
   at Microsoft.Office.InfoPath.MsxmlNavigator.MoveToFirstChild()
   at MS.Internal.Xml.XPath.XPathChildIterator.MoveNext()
   at MS.Internal.Xml.XPath.ChildrenQuery.Advance()
   at MS.Internal.Xml.XPath.ChildrenQuery.Advance()
   at MS.Internal.Xml.XPath.XPathSelectionIterator.MoveNext()
   at System.Xml.XPath.XPathNavigator.SelectSingleNode(XPathExpression expression)
   at System.Xml.XPath.XPathNavigator.SelectSingleNode(String xpath, IXmlNamespaceResolver resolver)
   at ProductCodeAdmin20090903.FormCode.GetProductNode()
   at ProductCodeAdmin20090903.FormCode.GetxpnProduct()
   at ProductCodeAdmin20090903.FormCode.Populate()
   at ProductCodeAdmin20090903.FormCode.Populate_Clicked(Object sender, ClickedEventArgs e)
   at Microsoft.Office.InfoPath.Internal.ButtonEventHost.OnButtonClick(DocActionEvent pEvent)
   at Microsoft.Office.Interop.InfoPath.SemiTrust._ButtonEventSink_SinkHelper.OnClick(DocActionEvent pEvent)

Any thoughts?

Hi GMLear (btw, I laughed at your icon!).

From the stack trace, I'm guessing that your code generates an xpath that is invalid because the node it references doesn't exist.  

 Glad you liked my avatar--it expresses how I feel most of time when dealing with this technology. 

I'm afraid it's not the code--the code works on my computer.  Found one blog that said it's a 3.5 Framework issue, and to roll back to 2.0!  Another one tells me that I need to set the form to full trust and either publish with a certificate or install using regform.exe.  Another states that I need to remove the SharePoint site from the trusted site list in the user's browser. 

I'm just going to plow through each solution and see if one works.

 I should've mentioned... The system generates a different, unique stack trace for each of the features I've programmed into the form.  And some of these don't necessarily perform a node test.