[horde] Horde/Imp replacement issues

[David Flood]

I'm fairly new to Horde/Imp but have recently been given the task of updating our old 
horde/Imp setup.

In order to do this I also needed to update php as well as horde and imp which I did. 
Unfortunately I can't get logged into either horde or imp although the 
/horde/imp/test.php works using the imap protocol. When I attempt to log into imp the 
page goes to /horde/imp/redirect.php but remains a plain white screen.

I'm using or attempting to use it through https (i.e. 
https://www.example.com/horde/imp), I did copy it to http but the same still happens.

I'm running:

apache 1.3.17
php 4.3.2
Horde 2.2.3
Imp 3.2

Any help would be gratefully received as the upgrading of php seems to have broken 
the old installation of horde/imp and my users don't have any way at the moment of 
checking their mail externally.
David Flood
Systems Administrator