[imp] Imap-Login works, don't get to mailbox

[Arthur]

Hi everybody

I've installed IMP on a Solaris 7 machine with the latest apache 1.3.x,
php 4.2.1 and mod_ssl. It seems to work allright. horde/imp/test.php
shows me the correct number of mails in my mailbox. But whenever I try
to log in I simply stay on the login screen while the URL gets a bit
longer with session-info. If I type a wrong password, I get a message
that the login failed. So imap authentication seems to work. Under
horde/ I even can logout after login in (to nowhere).

I can't find a horde.log file anywhere, I've checked that it has write
access to it.

I'm already at a point where I pay a pizza to whomever can solve my
problem (payable by credicard or paypal)....

Any help appreciated.

Arthur