Can't Log in to IMP 3.0 on debian

[Sam Rowe]

Hi,
Fresh install of IMP3.0 and HORDE2.0 on Debian/testing.

test.php works great, but complains about the lack of mcrypt support in
debian's PHP. I read that this will not break Horde/IMP, so I continued.
If I type
https://www.my.org/horde/imp/
    ^
in my browser I get redirected to
http://www.my.org/horde/imp/login.php?=b46de6118c70a840fe541f95fb593b3b&=c59172fed2521e299f1bba5ca93b0a59
Note no 's' in the service/proocol name. This is even with
$conf['use_ssl'] = 1;

Second problem:
When I try to log in, I'm given "Your Mail session has expired. Please
login again." I checked the mail list archives and found that in most
cases this was a typo in the config file for horde. I've been up and
down that file, using the .dist one to make as few changes as possible
and I can't find any errors.

I'm using mysql for the prefs backend, but even when I set prefs to
'none' I have the same problem.

Should redirect.php be adding all that session info to login.php before
an attempt has been made to login?

It also appears that 3 session cookies are generated whenever login.php
is loaded. Is that the way it should be?

Is my problem most likely a horde problem or an IMP problem?

BTW, my IMAP server shows a successful login each time an attempt is
made.

What can I do to help debug this? I've got logging turned on and set to
E_ALL but /tmp/horde.log is never created and if I create it, it stays
at 0 bytes.

Thanks for any help,
Sam