Some users won't login to Horde

[Nathan Carter]

Hi all,
I am having some issues with some of my users not being able to log
into Horde. Some users are able to get in while others just time out
while loading the initial screen.

My horde.log shows:
May 19 18:25:45 HORDE [debug] [horde] Max memory usage: 6291456 bytes
[pid 11889 on line 339 of
"/kolab/var/kolab/www/client/lib/Horde/Registry.php"]
May 19 18:25:45 HORDE [debug] [turba] Hook _horde_hook_share_init in
application horde not called. [pid 11889 on line 1683 of
"/kolab/var/kolab/www/client/lib/Horde.php"]
May 19 18:25:46 HORDE [debug] [kronolith] Hook _horde_hook_share_init
in application horde not called. [pid 11889 on line 1683 of
"/kolab/var/kolab/www/client/lib/Horde.php"]
May 19 18:27:05 HORDE [debug] [kronolith] Max memory usage: 67108864
bytes [pid 11889 on line 339 of
"/kolab/var/kolab/www/client/lib/Horde/Registry.php"]
May 19 18:27:05 HORDE [debug] [kronolith] IMAP errors: SECURITY
PROBLEM: insecure server advertised AUTH=PLAIN SECURITY PROBLEM:
insecure server advertised AUTH=PLAIN [pid 11889 on line 175 of
"/kolab/var/kolab/www/client/imp/lib/IMAP.php"]
May 19 18:27:06 HORDE [debug] [kronolith] Hook _horde_hook_share_init
in application horde not called. [pid 16704 on line 1683 of
"/kolab/var/kolab/www/client/lib/Horde.php"]
May 19 18:29:36 HORDE [debug] [kronolith] Max memory usage: 66846720
bytes [pid 16704 on line 339 of
"/kolab/var/kolab/www/client/lib/Horde/Registry.php"]
May 19 18:29:36 HORDE [debug] [kronolith] IMAP errors: SECURITY
PROBLEM: insecure server advertised AUTH=PLAIN SECURITY PROBLEM:
insecure server advertised AUTH=PLAIN [pid 16704 on line 175 of
"/kolab/var/kolab/www/client/imp/lib/IMAP.php"]

Thanks in advance