[imp] imp login problem

[chao lin]

Hi, I have a login problem after I upgrade php from 4.0.6 to 4.1.2,
I used redhat7.2, horde2.0, imp3.0, courier-imap1.4.2. I can login over imap
plain and imap/ssl(using outlook express). But when I login using imp, it has
the following error message in horde.log.

HORDE [error] [imp] FAILED LOGIN x.x.x.x to 127.0.0.1:143[imap] as test [on line
332 of "/var/www/html/horde/imp/lib/IMP.php"]

I welcome any hints as to what's causing this problem. Thanks in advance!

chao