I've installed it using the Strawberry cpan client, it installs fine ...
Do you mean that all of the tests passed ? (Surely not.)
One would expect that all tests would have failed with the exact same error as you've reported, and that you would have had to use force to effect the installation of XML::LibXML.
Otherwise you've invented some (hitherto unknown) way of breaking a perl installation.
I take it that the error can be produced by running simply: