i posted my problem to various newsgroups but until now i got no answer
which helped me to solve it.
So i try it  here - as the problem is related to VB.NET
If anybody can give me an advice about another newsgroup which maybe able to
help me i would also be happy about it.
(in my mind this is a general problem and ther should be an answer out
there)

The problem:

we use character refrences in our XML data

like:  ß    Schließer   : UNICODE for ?
       Ö    Öffner      : UNICODE for ?

this is a valid way to encode UNIcode characters in XML
and normally this works fine (in VB6 and in IE6)

But if i perfom the XSL Transformation in VB.NET with

 Dim xslt As New System.Xml.Xsl.XslTransform()
 Dim out As System.IO.StreamWriter
 Dim writer As New System.Xml.XmlTextWriter(out)

and i load the resulting HTM File into my Browser (IE6.0) then the display
is

Schlie?Yer instead of Schlie?er
and
?-ffner    instead of ?ffner

(if a perform the conversion "on the fly" in IE6.0 it is OK - but this does
not help me as i need
 to generate HTML files as result)

BUT ß is the valid UNICODE refrence for ?

Either i am doing something wrong or VB.NET does not work correctly here.

Bug or feature ???

Greetings
     Michael

Dim xslt As New System.Xml.Xsl.XslTransform()
Dim out As System.IO.StreamWriter

out = File.CreateText(m_strActDir + "\out.htm")

xslt.Load("file://" + m_strActXSL)
Dim xpathdocument As New System.Xml.XPath.XPathDocument("file://"
+ m_strActXML)

Dim writer As New System.Xml.XmlTextWriter(out)

writer.Formatting = System.Xml.Formatting.Indented

xslt.Transform(xpathdocument, Nothing, writer)
writer.Close()

Style Sheet:

<xsl:stylesheet version="1.0"
xmlns:xsl=" http://www.*-*-*.com/ ;
xmlns:msxsl="urn:schemas-microsoft-com:xslt">
<xsl:output method='html' encoding='ISO-8859-1'   omit-xml-
declaration='yes'/>

<xsl:template match="/">
...

XML Dok. sample:

<?xml version='1.0'?> <!DOCTYPE topic SYSTEM 'MedaPS2.dtd'>
<?xml-stylesheet href="medaps_convert2HTML.xsl" type="text/xsl"?>
<topic>

<metalist>

<meta name="Generator" value="SCHEMA MarkupKit 2.0"/>
</metalist>

<mtable>
<table hsdl-percent="21.1 8.5 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7"
type="t_TDv">
<thead>
<tr>
<th><p>Schalten von Lasten<br/>Insta Sch&#252;tze 5TT3 7</p></th>
<th></th>
<th><p>20 A</p></th>
<th><p>21 A</p></th>
<th><p>24 A</p></th>
<th><p>25 A</p></th>
<th><p>40 A<br/>Schlie&#223;er</p></th>
<th><p>40 A<br/>&#214;ffner</p></th>