Comment 11 for bug 287488

I have a similar problem (found via http://ubuntuforums.org/showthread.php?t=965001) with a user on a Kubuntu system.

I tried updating kdebase-workspace from intrepid-proposed but the problem still exists.

Background:
1. System was previously Hardy with KDE4 and KDE3.5.10 installed
2. 2 users: one using KDE4, one using KDE3
3. Updated to Intrepid, KDE4 only
4. The user who was KDE4 only can log in ok and run KDE4
5. The user who was KDE3 (now KDE4) only gets the KDM greeter, enters password and blank screen with a mouse pointer is seen.
6. Restart X (Ctrl-Alt-Backspace) to get back to KDM greeter : goto 5

The KDE3 user does not have sudo privs if that helps (I notice the permission denied errors? ) Maybe they don't belong to a required group on the system and cannot read the files required ?

.xsession-errors shows some failures as noted in previous comments and that forum link:

$ cat .xsession-errors
Xsession: X session started for tamara at Sat Nov 15 11:06:43 EST 2008
/etc/X11/Xsession.d/40guidance-displayconfig_restore: line 11: /usr/bin/displayconfig-restore: No such file or directory
Setting IM through im-switch for locale=en_AU.
Start IM through /etc/X11/xinit/xinput.d/all_ALL linked to /etc/X11/xinit/xinput.d/default.
/usr/bin/xmodmap: unable to open file '/usr/share/apps/kxkb/ubuntu.xmodmap' for reading
/usr/bin/xmodmap: 1 error encountered, aborting.
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
kwin(7123) KDecorationPlugins::loadPlugin: kwin : path "/usr/lib/kde4/kwin3_ozone.so" for "kwin3_ozone"
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
kwin(7123) KToolInvocation::klauncher: klauncher not running... launching kdeinit
kdeinit4: preparing to launch /usr/lib/kde4/libexec/klauncher
kdeinit4: preparing to launch /usr/bin/kded4
kdeinit4: preparing to launch /usr/bin/kbuildsycoca4
kbuildsycoca4 running...
kdeinit4: preparing to launch /usr/lib/kde4/libexec/kconf_update
kdeinit4: preparing to launch /usr/bin/knotify4
kwin(7123): Couldn't start knotify from knotify4.desktop: "KDEInit could not launch '/usr/bin/knotify4'."

NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
x-window-manager: Fatal IO error: client killed
QObject: Do not delete object, 'unnamed', during its event handler!
QObject: Do not delete object, 'unnamed', during its event handler!
QObject: Do not delete object, 'unnamed', during its event handler!
kdeinit4: Fatal IO error: client killed
klauncher: Exiting on signal 15
kded4: Fatal IO error: client killed
XIO: fatal IO error 4 (Interrupted system call) on X server ":0.0"
      after 25 requests (8 known processed) with 0 events remaining.
knotify4: Fatal IO error: client killed

=========

And another attempt at login:
$ cat xsession-errors-login-20081115-2
Xsession: X session started for tamara at Sat Nov 15 10:44:46 EST 2008
/etc/X11/Xsession.d/40guidance-displayconfig_restore: line 11: /usr/bin/displayconfig-restore: No such file or directory
Setting IM through im-switch for locale=en_AU.
Start IM through /etc/X11/xinit/xinput.d/all_ALL linked to /etc/X11/xinit/xinput.d/default.
/usr/bin/xmodmap: unable to open file '/usr/share/apps/kxkb/ubuntu.xmodmap' for reading
/usr/bin/xmodmap: 1 error encountered, aborting.
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
kwin(8194) KDecorationPlugins::loadPlugin: kwin : path "/usr/lib/kde4/kwin3_ozone.so" for "kwin3_ozone"
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
kwin(8194) KToolInvocation::klauncher: klauncher not running... launching kdeinit
kdeinit4: preparing to launch /usr/lib/kde4/libexec/klauncher
kdeinit4: preparing to launch /usr/bin/kded4
kdeinit4: preparing to launch /usr/bin/kbuildsycoca4
kbuildsycoca4 running...
kdeinit4: preparing to launch /usr/lib/kde4/libexec/kconf_update
"KConfigIni: In file /tmp/kde-tamara/kconf_updatevC8277.tmp, line 1: " Invalid entry (missing '=')
kded(8274): Communication problem with "kded" , it probably crashed.
Error message was: "org.freedesktop.DBus.Error.NoReply" : " "Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken." "

kded(8275): "KLauncher could not be reached via D-Bus. Error when calling kdeinit_exec_wait:
empty
"

kdeinit4: preparing to launch /usr/bin/knotify4
kwin(8194): Couldn't start knotify from knotify4.desktop: "KDEInit could not launch '/usr/bin/knotify4'."

NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
NVIDIA: Direct rendering failed; attempting indirect rendering.
kwin(8194) KDecorationPlugins::loadPlugin: kwin : path "/usr/lib/kde4/kwin3_ozone.so" for "kwin3_ozone"
QObject: Do not delete object, 'unnamed', during its event handler!
QObject: Do not delete object, 'unnamed', during its event handler!
QObject: Do not delete object, 'unnamed', during its event handler!
x-window-manager: Fatal IO error: client killed
kdeinit4: Fatal IO error: client killed
klauncher: Exiting on signal 15
kded4: Fatal IO error: client killed
knotify4: Fatal IO error: client killed
XIO: fatal IO error 104 (Connection reset by peer) on X server ":0.0"
      after 25 requests (8 known processed) with 0 events remaining.

========================

System is:
Dell XPS 1330
NVIDIA 8600 using nvidia binary via ubuntu repos
KDE 4.1.3
Kubuntu 8.10

I'm probably going to end up deleting this user and recreating their account.