VS 2008 - XML Cleanup With Missing Tags

I am trying to format xml entries I have so that I can use the xmltextreader without getting errors. I added a default header and footer in the event I notice there is no opening or closing tags. I remove illegal characters and check for unicode but I always find an issue where an entry slips in and gives the error: data at the root level is invalid and when I check that entry is slipped through the cleaning process or just has an unmatched tag somewhere.

Now I use
Dim stringSplitter() As String = {"</entry>"}
' split the file content based on the closing entry tag
sampleResults = _html.Split(stringSplitter, StringSplitOptions.RemoveEmptyEntries)
To split my xml into individual entries before I start the cleanup process.

Here are my default headers:
Private defaultheader = "xmlns=""[URL]"""
Private headerl As String = "<?xml version=""1.0"" encoding=""utf-8""?>" & vbNewLine & "<entry " & defaultNameSpace & ">"
Private footer As String = "</entry>"

Is there any tool in the .net framework that can detect and cleanup unmatched tags so that I can get this to work.