Errors on XML Transform after upgrading to 10g

Hi,

we have upgraded from 9.2.0.5 to 10.2.0.4 on Solaris 10 and we are now getting the following errors on an XML transform:

ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00654: Output namespace attribute 'xmlns' doesn't have a parent element.
ORA-06512: at "SYS.XMLTYPE", line 174
ORA-06512: at line 30

Below is a cutdown version of the procedure that we are running but it does recreate the issue.  If you run this bit pl/sql  under 10.2.0.4 you get the errors above, but if you run it under 9.2.0.5 it works? 

declare
p_xml xmltype ;
x_xml xmltype ;
begin
x_xml := xmltype('<xsl:stylesheet version="1.0" xmlns:xsl="