hi everyone!

i have installed fedora core 5 a few weeks ago and so far everything was working ok.
at last i tried to install a mail program called postfix. now i have problems with booting (vnc viewer crashed!):

like the following:
when i boot up the system i dont see the login screen. i just see a black screen and the harddrive is working really heavy. when i press ALT-CTRL-F1 i can see the login screen. then i login and look at the system control tool which tells me that 80% of the CPU is being used by PREFDM. also the harddrive is working heavy. when i stop the process PREFDM everything seems to be normal. i am just not able to have access to the command line full screen.

anyone knows about this problem?
i will post the content of my /etc/X11/prefdm here:
#########################################
#!/bin/sh

PATH=/sbin:/usr/sbin:/bin:/usr/bin

# shut down any graphical boot that might exist
if [ -x /usr/bin/rhgb-client ]; then
/usr/bin/rhgb-client -quit
fi

# We need to source this so that the login screens get translated
[ -f /etc/profile.d/lang.sh ] && . /etc/profile.d/lang.sh

# Run preferred X display manager
preferred=
if [ -f /etc/sysconfig/desktop ]; then
. /etc/sysconfig/desktop
if [ "$DISPLAYMANAGER" = GNOME ]; then
preferred=/usr/sbin/gdm
elif [ "$DISPLAYMANAGER" = KDE ]; then
preferred=/usr/bin/kdm
elif [ "$DISPLAYMANAGER" = XDM ]; then
preferred=/usr/bin/xdm
elif [ -n "$DISPLAYMANAGER" ]; then
preferred=$DISPLAYMANAGER
fi
fi

shopt -s execfail

# If we're in early-login mode and something is running, bail out
if grep -q early-login /proc/cmdline 2> /dev/null ; then
if [ -n "$preferred" ]; then
pidof $preferred >/dev/null 2>&1 && exit 0
fi
pidof gdm-binary >/dev/null 2>&1 && exit 0
pidof kdm >/dev/null 2>&1 && exit 0
pidof xdm >/dev/null 2>&1 && exit 0
fi

if [ -n "$preferred" ]; then
$preferred "$@" >/dev/null 2>&1
if [ $? -ne 127 ]; then
exec $0 "$@"
exit $?
fi
fi

# Fallbacks, in order
gdm "$@" >/dev/null 2>&1
if [ $? -ne 127 ]; then
exec $0 "$@"
exit $?
fi
kdm "$@" >/dev/null 2>&1
if [ $? -ne 127 ]; then
exec $0 "$@"
exit $?
fi
xdm "$@" >/dev/null 2>&1
if [ $? -ne 127 ]; then
exec $0 "$@"
exit $?
fi

# catch all exit error
exit 1


--------
ok now when i look in the file /var/log/messages it says:

Sep 13 14:22:42 localhost gdm[3736]: GDM is already running. Aborting!
Sep 13 14:22:42 localhost gdm[3765]: GDM is already running. Aborting!

and so on. the log file is 26.8 MB !!!!