[gdm-list] login problem: "Cannot run seteuid to 0: Operation not permitted"

[Renato Budinich <rennabh gmail com>]

Hello, I did a fresh install of Zenwalk 6.2 (Slackware based distribution) which as far as I understand uses gdm as a login manager. I can login as root. As a normal user, though, I get a pop up window saying:

 (translated)
"Session lasted less than 10 seconds. If you haven't
explicitly logged out, it's possible that there has been problems
during installation or that there's no space left on disk. Try to use
one of the emergency sessions to solve the problem"

btw I have lots of free disk space.

in my home directory the file .xsession-errors reads:
"/etc/X11/gdm/Xsession: line 81: exec: default: not found"

lines 80-81 of "/etc/X11/gdm/Xsession read: 
"#if a particular session type was requested in $SESSION, start that session
exec $SESSION"

If in /etc/X11/gdm/Xsession I change the line 26 (first command after a small 'if' to redirect errors to users' home if possible) from
SESSION = "$@"
to 
SESSION = "gdm"

I
get another error when I try to login - the window of the session
lasting less than 10 seconds is the same, but my ~/.xsession-errors reads:

"gdm-binary[2922]: WARNING: GDM file gdm-daemon-config.c: line 2041 (): Cannot run seteuid to 0: Operation not permitted
GDM file gdm-daemon-config.c: line 2041 (): Cannot run seteuid to 0: Operation not permitted"

I guess this is the real error. It seems like a permission issue to me, but I can't understand which file to check. 'locate gdm-daemon' gives nothing (have done updatedb first).

I've also asked this on the zenwalk forum, but haven't come to a solution. for reference, here is the link:
http://support.zenwalk.org/viewtopic.php?f=10&t=26441


hope I provided enough info
Renato