[imp] IMP 3 - no login, just horde modules

[Michael Bull]

Morning all:
Looking to get IMP 3 working - I've installed the files and am trying to
configure things up.  Apache/PHP are no problem, and I made the changes
in the registry.php for horde to set IMP for authentication... however
all I'm seeing is a page that is empty except for the horde modules line
at the bottom, listing horde, mail, and logout.

I've obviously missed something - I haven't seen the answer in the list
bit this is harder to search for, and I tried to find it in the faq. 
Any ideas what I need to look at here?

Thanks.