[imp] imp auth problem

[Andrew Roseman]

Hello,
I have been using Horde/IMP for 4yrs now, with many installations, but i
have just downloaded and installed the latest version of Horde 2.2.7 and IMP
3.2.6 and I am having problems with IMP auth for horde

I have uncomment the two lines in config/registry.php

$this->registry['auth']['login'] = 'imp';
$this->registry['auth']['logout'] = 'imp';

and the horde.php is
$conf['auth']['driver'] = ''

I get in the horde log file
Nov 16 11:37:15 HORDE [notice] [imp] Login success ...

When you click on Login, it takes you back to the login screen!!! not into
IMP.

I have tested logging into IMP (/imp/login.php) direct and it works fine, I
have disabled "imp auth", and setup in horde.php $conf['auth']['driver'] =
'imap'; and it authenticates successfully (requesting the double login)

Nov 16 11:40:14 HORDE [info] [horde] Login success...
Nov 16 11:40:39 HORDE [notice] [imp] Login success...

Versions:
PHP Version: 4.3.3
Apache/2.0.47

Please advise if I need to provide any more information...and I hope someone
can assist

Thanks
Andrew