[imp] Using IMP in a sub domain

[Nicolas [HiTech Planet]]

> nope, this sounds more like an apache (or whatever you use to dish up your
> webpages) issue. If it is apache, check out your <VirtualHost>
(ServerName)
> directives, assuming you are using this to handle your domain names.

The Apache configuration of my host seems ok, but some pages are not loaded
into the browser, and I really don't know why. If you look at this address :
http://email.hitechplanet.com/horde/imp/, you'll just get a 404error... same
thing here : http://www.hitechplanet.com/email/horde/imp/. Now if you go
there : http://email.hitechplanet.com/login.php, it will work, this is the
custom login page. But, trying to login with login : 'test@hitechplanet' and
pass : 'test', it won't load the redirect.php page... without giving any
error.
If you could help, it would be great. Thank you anyway.