SL6: Non-standard home directories, Error: `Could not chdir to home directory` upon login, but `cd $HOME` works?
It could be an SELinux issue. Check /var/log/audit/audit.log for any related messages. See this informative post for more information, including a possible fix:
# chcon -t home_root_t /homedir/stefanl
The correct command without setting SELinux to permissive is:
#chcon -t home_root_t /homedir
(note the missing stefanl directory)