[imp] imap connections break on attachments

[Sean D.]

i get this error log when i try to click on an attachment to, for example, view 
a jpeg in a new window:

[client 67.173.xx.xx] PHP Notice:  (null)(): [CLOSED] IMAP connection broken 
(server response) (errflg=2) in Unknown on line 0, referer: 
https://webmail.xxxxxxxxxxx.net/horde/imp/message.php?index=5164

Server is:
RHEL3 (Taroon 3)
PHP 4.3.9
Apache 2.0.46
Courier IMAP 3.0.3 (running on localhost)
MySQL 3.x
Qmail 1.13

normal IMAP (using client software) works fine.

downloading the attachment instead of viewing it doesnt work either... examining 
the downloaded attachment in a text editor shows that it is filled with the same 
error as above.

I dont necessarily think this is a horde problem but i cant find anything wrong 
with apache, php, or courier.  maybe its pear?  i'm using the version on 
ftp.horde.org. any suggestions?

thanks in advance,
Sean D.