weird login problem

[caribbeanknight]

Hi,
I have installed roundcube-0.2.1 on gentoo but I have some weird problems:

* When I try to login, some users have no trouble at all, everything works.
* But when I try to login with some other users the login screen stays there for about 2 minutes till returning to the empty login screen. I noticed while this delay is happening my apache PID is taking about 99% of my CPU resources.

Anyone have an idea while this is happening?