I am having this same problem.
I thought this might help with some troubleshooting of why this is happening....
My problem: I had a perfectly good, running Plesk server. Everyone loved Horde. I loved using my Horde!
Horde is not currently working, I get a blank page in Firefox, and in Safari, I get a dropped connection.
The error I am getting in Apache
/var/log/apache2/error_log
is:
[Wed Jan 02 12:47:53 2008] [error] [client xx.xxx.xxx.xx] File does not exist: /usr/share/psa-horde/favicon.ico
/usr/sbin/httpd2-prefork: symbol lookup error: /usr/lib64/php5/extensions/gettext.so: undefined symbol: php_realpath
Restoring from a complete backup after a 'disaster', I restored my system after a basic install of Plesk 8.2.
Restore backup file - (complete server level)
EVERYTHING WORKS GREAT except HORDE!
So, I poke around and look on the blogs, Plesk 8.3 is supposed to have updated rpm's, so I do the upgrade hoping Horde would get fixed in the process.
Not happening. Horde still not working, server working great except, nobody can get their webmail, and I am frantically setting up OUTLOOK and MAIL on all my client's boxes.
SUSE, 64 bit Xeon, Plesk 8.3 updated. Obviously the php5 incompatibility issue is making horde cease to work on the server.
What is a good solution to get Horde working again, now that pandora's box has been opened, and horde is broken?
Thanks
Tregtronics