Error: "Invalid byte 1 of 1-byte UTF-8 sequence" ?

I got a XML doc and a java class which should process this XML doc (on WinXP-OS).

Unfortunately I am getting an execption:

"Invalid byte 1 of 1-byte UTF-8 sequence" 

What's wrong?

Because I have not the java source I can only change the XML doc.
The XML doc starts:

<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
....

It could be that there are some line end conversion errors when I downloaded the XML file from 
Linux server.

Could this be the problem ?

Ben