NullPointerExceptionが発生するのはバグ以外の何者でもないだろ、常識で考えて……

Parameters:
in - the input stream from which to read the XML document.
Throws:
IOException - if reading from the specified input stream results in an IOException.
InvalidPropertiesFormatException - Data on input stream does not constitute a valid XML document with the mandated document type.
NullPointerException - if in is null.

http://java.sun.com/j2se/1.5.0/docs/api/java/util/Properties.html#loadFromXML(java.io.InputStream)

あ、あほか！！！