[horde] Horde2 Debian Install

[Kat Goodwin]

Hi,

I'm running the debian packages of Horde2 (version 2.2.3-6) and imp3
(version 3.2.2-3) and I get the following error at the top of the login
page:

Warning: Cannot modify header information - headers already sent by
(output started at /etc/imp3/servers.php:30) in
/usr/share/horde2/lib/Secret.php on line 144

It does allow me to log in, but I get the same error message after login. 
If I then follow the links at the bottom, I can see my inbox.

This has completely stumped me, so any help would be really appreciated!

If anyone can help, and needs more information from me, please let me know.

thanks

Kat