[eluser]Dan Hulton[/eluser]
I had this problem at one point when I was integrating it into another of my projects, and I'd realized that I'd forgotten to enable hooks in config.php -- you may want to double-check that. While you're at it, you might want to check and ensure that the hooks are added correctly, too.
Aside from that, you've got a real head-scratcher there. Is the rest of your application displaying as normal, or do you get only a blank page? I find that if the error log directory or the cache directory aren't writable by the webserver, CI will just serve a blank page. Perhaps you're running across that?
Let me know if that resolves your issue, or if not, again get in touch with me and we can work together to get it running. =)