su: authentication failure

[Sebastiaan <sebas@sacred-key.org>]

Hello,

I am unable to 'su' to root or any other user (except
when being root). 
/var/log/auth.log tells me this:

unix_checkpwd: check pass: user unknown
PAM_unix: authentication failure; sebastia(uid=1000) -> root for su service
pam_authenticate: Authentication failure


I feel I have to tell some 'history' about my computer. Today I set up a
diskless client (the computer with su problems). After I configured the
server I did a fresh install from the client on the remote
harddisk. Everything seems to work well, except for some errors the server
encounters. I see the following errors dumped on the server screen:

fh_verify: log/wdm.log permission failure, acc=2, error=13
fh_verify: run/atd.pid permission failure, acc=1, error=13

I run potato on both systems, both fresh install. I use the nfs-kernel
package and use this /etc/exports:

/tftpboot/compu
192.168.1.1(rw,no_root_squash,nohide,subtree_check,insecure_locks,insecure)

I think the problem is here somewhere. 

Any hints, ideas?

Thanks,
Sebastiaan