Cloning was the way to go. This is the new code. However, I would like to know why I have to clone to avoid this situation.

        ' Get a XML node attribute
        ' expC1 Node
        ' expC2 Attribute
        Public Function GetXMLNodeAttributeValue(ByVal tcNode As String, ByVal tcAttribute As String) As Boolean
            Dim llFound As Boolean = False
            Dim loAttribute As XmlAttribute = Nothing

            ' Reset the values
            cMessage = ""
            cNodeAttribute = ""

            ' If we have a content
            If Not oXmlAttributeCollection Is Nothing Then
                oXmlAttributeCollection.RemoveAll()
            End If

            ' Select the node
            If oXmlNameSpaceManager Is Nothing Then
                oXmlNode = oXmlDocument.SelectSingleNode(tcNode)
            Else
                oXmlNode = oXmlDocument.SelectSingleNode(tcNode, oXmlNameSpaceManager)
            End If

            ' If the node does not exist
            If oXmlNode Is Nothing Then
                cMessage = oApp.StrTran(cNodeDoesNotExist, "##Node##", tcNode)
                Return False
            End If

            ' Assign the new attributes to this object
            oXmlAttributeCollection = oXmlNode.Clone.Attributes

            ' Scan the attribute collection
            For Each loAttribute In oXmlNode.Attributes

                ' If this is the one
                If UCase(loAttribute.Name) = UCase(tcAttribute) Then
                    cNodeAttribute = loAttribute.Value
                    llFound = True
                    Exit For
                End If

            Next

            ' If we did not find it
            If Not llFound Then
                cMessage = oApp.StrTran(cAttributeDoesNotExist, "##Attribute##", tcAttribute)
                Return False
            End If

            Return True
        End Function