[imp] PHP Notice in error-log

[Silver Salonen]

Hi!

I run horde-3.0.9, imp-4.0.4, php-4.4.0 and chrooted Apache-1.3 on 
FreeBSD-5.4 set up with OpenLDAP (authenticating users from there).

Everything is fine, but sometimes an user can't forward or reply an e-mail - 
browser can't connect to server - it times out or says that the page cannot 
be displayed or doesn't say anything at all. Especially if it has some bigger 
attachment, but sometimes even without any.

In Apache I have limited memory for Horde (now it has 24 MB, but it still got 
those failures).

The only error I see in virtualhost's error-log is:
[Thu Jan 12 11:04:15 2006] [error] PHP Notice:  Only variable references 
should be returned by reference in /usr/local/www/horde/lib/Horde/
MIME/Message.php on line 264

Is it supposed to be there or have I misconfigured something?

Thanks for any suggestions,
Silver