imap_open hangs...

Hi, I have a script which works fine for many users, but for some it doesn't. I've been able to narrow it down to the imap_open-Command which just hangs 'forever'. I have verified that the imap-extensions are available, but other than that I have no ideas what's going on there, why it would not respond and what I could possibly do to avoid such errors. I assume something must be missing/wrong in the PHP-setup, i.e. I've had other cases where imap-extensions were included at compile-time, but not loaded due to an error with the RAND_seed symbol etc. - but in all those cases there was at least an error-msg telling you something was wrong. But just silently dying is not a very helpful :( Any ideas anyone? Thanks Michael