[horde] Problems logging in

[Norman]

I'm suddenly having problems logging into my horde/imp setup, though it had
been working for months (since I initially installed horde 2.0 and imp 3.0,
and then on older versions).  I'm not able to identify anything within my
horde heirarchy that has been changed in the past few days.  I'm using imap
for authentication, and have verified that I can login to the imap server
via 'telnet localhost 143'.  I also have verified imap/php via Netscape's
mail client, and a quick squirrelmail install (after imp, it's a major
step down).

/horde/test.php shows everything looking good.

Problems are existing with horde/imp 2.0/3.0 and 2.1/3.1, and is happening
in both the horde and imp logins.

I'm running RedHat 7.2, and use up2date to update my system RPMs.  I had updated
just prior to the problems, but removing the updated RPMs, and then installing
the older revisioned RPMs from CD did not fix the problem, so I re-updated.

I am seeing the following in my log files that corresponds to when I'm
attempting to login:

  Aug 22 09:40:18 lucky imapd[12184]: imap service init from 127.0.0.1
  Aug 22 09:40:18 lucky imapd[12184]: Command stream end of file, while reading line user=??? host=UNKNOWN
  Aug 22 09:40:18 HORDE [error] [imp] FAILED LOGIN 192.9.51.3 to lucky:143[imap] as yourdog [on line 270 of "/opt/horde-2.1/imp-3.1/lib/IMP.php"]

Can someone provide any pointers on helping me debug and fix this issue?

Thanks,
Norman