After a lot of mucking around I finally have this working. I have this installed on a Linux server and noticed that some of the functions used in this module are from the php-domxml extension. I asked my website host to install this for me and it worked - Magic.
Oh, and I think with a Windows server you need to ensure that the domxml.dll has been installed, but I don't really know much about Windows servers.
I hope that this helps someone else.