[imp] IMP suddenly causes an error 403 when logging in

[Brian Voils]

I was able to use IMP just fine a couple hours ago.  I closed my web
browser, and left the computer for about 3 hours.  I then came to log
into Horde/IMP to check my mail, and received an Error 403 when
accessing IMP.  I can log into Horde just fine, and can use Turba just
fine.  Whenever I try to access IMP, however, I get the error 403. 
Any ideas what's going on?

It's installed on a shared server, and I don't have shell access. 
They do have a terrific helpdesk, however, and can do just about
anything on the shell for you, if needed.  I have FTP access and do
have filesystem access, however.

Anyways ...
Here is the last webserver log entry when it worked:
68.113.40.92 - - [26/Nov/2005:21:35:14 -0500] "GET
/horde/imp/mailbox.php?Horde=b71ac5ea904ecdbad7a4a6121df236e4&page=1&uniq=64043947243891a3272c00
HTTP/1.1" 200 36344 "-" "Mozilla/5.0 (X11; U; Linux i686; en-US;
rv:1.7.12) Gecko/20050920 Firefox/1.0.7"

And here is the next log entry accessing IMP:
68.113.40.92 - - [27/Nov/2005:00:23:12 -0500] "GET
/horde/imp/mailbox.php?Horde=5e40fcccee43bf3d6ae5d12370b07d7b&mailbox=INBOX&actionID=105
HTTP/1.1" 403 667 "http://voils.net/horde/imp/" "Mozilla/5.0 (X11; U;
Linux i686; en-US; rv:1.7.12) Gecko/20050920 Firefox/1.0.7"



Version Information:
IMP Version 3.2.3
Horde Version 2.2.5
PHP Version 4.3.11
Apache/1.3.33 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2
mod_bwlimited/1.4 PHP/4.3.11 FrontPage/5.0.2.2635 mod_ssl/2.8.22
OpenSSL/0.9.7a
Linux server54 2.4.21-32.0.1.ELsmp #1 SMP Wed May 25 14:26:33 EDT 2005 i686

--
Brian Voils