[imp] test.php not working on port 80 but works on 2082

[dave at orangechicken.com]

My host uses CPanel and has Horde webmail.

Under port 2082, the imp test.php works just fine. The same php page in my
directory under port 80 fails (network error - imap_open is segfaulting the
Apache child (I believe) whenever I try to access the imap server).

What could possibly cause this? I need some info to persuade my host that it's
not a Cpanel nor Imp issue, but a configuration error on their part.

Strange thing is, it worked last night for about 14 hours and then suddenly
stopped working - host says nothing changed.

Please please help... So far I've wasted about 40 hours trying to track this down.

-Dave