I am trying to do a XML::XPATH (out of CPAN) parse under windows

I presume you mean XML::XPath.

It appears that the XPATH module is confused about the g: windows device name and the mechanism specifier.

More specifically, the module assumes paths and URIs are interchangeable.

I've seen similar posts elsewhere on the net but never got a satisfactory answer.

There's a bug in the module that needs fixing. ( Actually, it would be in XML::Parser, XML::Parser::Expat or maybe even the C library expat. )

I bet XML::LibXML doesn't have that bug.