[CentOS] Login problem on CentOS 4.4 GDM

I have just restructured my system (repartitioned the main disk to separate /home from /) and I am now getting this error when I try to log in as a non-root user:

Your session only hasted less than 10 seconds. If you have not logged out yourself, this could mean that there is some installation problem or you may be out of disk space. Try logging in with one of the failsafe sessoions to see if you can fix this problem.

I can log in via ssh or as root, but I don't know what to fix. Since I can log in via ssh, I am assuming that I have enough disk space (there's plenty everywhere), so I'm thinking a config problem, but what?

Thanks.