Can't boot Xubuntu session after installing Lubuntu first and then xubuntu-desktop

[freaxtux]

Sorry if there's any awkward expression. I'm not a native English speaker.

First, I installed Lubuntu, which uses LXDM. After that, xubuntu-desktop was installed via apt-get with no option. I selected to use LXDM at the time. When I try to log in with Xubuntu Session with LXDM, It just goes back to ID-writing field. There was nothing special in /var/log/lxdm, and I can't find log file from xfce.

After that, I tried to use LightDM, but when I choose LightDM with "sudo dpkg-reconfigure lightdm" and boot with it, the console screen with X.org messages and blank-screen with a mouse cursor switches each other over and over, like blinking. Next is the log file generated when I stop LXDM and run LigntDM with --debug option in console.

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.0.1, UID=0 PID=1981
[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat

and then next part appears repeatdly

[+0.00s] DEBUG: Starting new display for greeter
[+0.00s] DEBUG: Starting local X display
[+0.00s] DEBUG: Using VT 7
[+0.01s] DEBUG: Activating VT 7
[+0.02s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.02s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.02s] DEBUG: Launching X Server
[+0.02s] DEBUG: Launching process 1986: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.03s] DEBUG: Waiting for ready signal from X server :0
[+0.04s] DEBUG: Acquired bus name
[+0.04s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+1.39s] DEBUG: Got signal 10 from process 1986
[+1.39s] DEBUG: Got signal from X server :0
[+1.39s] DEBUG: Connecting to XServer :0
[+1.40s] DEBUG: Starting greeter session
[+1.65s] DEBUG: pam_start("lightdm-autologin", "lightdm") -> (0x8c20088, 0)
[+1.65s] DEBUG: Starting session unity-greeter as user lightdm logging to /var/log/lightdm/x-0-greeter.log
[+1.66s] DEBUG: pam_authenticate(0x8c20088, 0) -> 0 (Success)
[+1.66s] DEBUG: pam_acct_mgmt(0x8c20088, 0) -> 0 (Success)
[+1.66s] DEBUG: Launching session
[+1.67s] DEBUG: pam_set_item(0x8c20088, 3, ":0") -> 0 (Success)
[+1.67s] DEBUG: pam_open_session(0x8c20088, 0) -> 0 (Success)
[+1.70s] DEBUG: Opened ConsoleKit session fafb29370bfd201066616b870000000c-1319041106.899262-1286802672
[+1.70s] DEBUG: Dropping privileges to uid 107
[+1.70s] DEBUG: Adding session authority to /var/lib/lightdm/.Xauthority
[+1.78s] DEBUG: Restoring privileges
[+1.78s] DEBUG: Launching process 2003: /usr/lib/lightdm/lightdm-greeter-session 'unity-greeter'
[+1.78s] WARNING: Failed to open log file /var/log/lightdm/x-0-greeter.log: Permission denied
[+1.78s] DEBUG: pam_setcred(0x8c20088, PAM_ESTABLISH_CRED) -> 0 (Success)
[+1.78s] DEBUG: PAM returns environment 'PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games LANG=ko_KR.UTF-8'
[+1.96s] DEBUG: Read 8 bytes from greeter
[+1.96s] DEBUG: Read 9 bytes from greeter
[+1.96s] DEBUG: Greeter connected version=1.0.1
[+1.96s] DEBUG: Wrote 99 bytes to greeter
[+1.96s] DEBUG: Greeter connected, display is ready
[+1.96s] DEBUG: New display ready, switching to it
[+1.96s] DEBUG: Activating VT 7
[+1.96s] DEBUG: Process 2003 exited with return value 0
[+1.96s] DEBUG: pam_close_session(0x8c20088) -> 0 (Success)
[+1.96s] DEBUG: pam_setcred(0x8c20088, PAM_DELETE_CRED) -> 0 (Success)
[+1.96s] DEBUG: pam_end(0x8c20088) -> 0
[+1.96s] DEBUG: Ending ConsoleKit session fafb29370bfd201066616b870000000c-1319041106.899262-1286802672
[+1.99s] DEBUG: Greeter quit
[+1.99s] DEBUG: Stopping display
[+1.99s] DEBUG: Sending signal 15 to process 1986
[+1.99s] DEBUG: Dropping privileges to uid 107
[+1.99s] DEBUG: Removing session authority from /var/lib/lightdm/.Xauthority
[+2.06s] DEBUG: Restoring privileges
[+2.07s] DEBUG: Process 1986 exited with return value 0
[+2.07s] DEBUG: X server stopped
[+2.07s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+2.07s] DEBUG: Releasing VT 7
[+2.07s] DEBUG: Display server stopped
[+2.07s] DEBUG: Display stopped
[+2.07s] DEBUG: Active display stopped, switching to greeter
[+2.07s] DEBUG: Switching to greeter

Giving "--test-mode" option makes no difference.

There's lines saying

[+1.65s] DEBUG: Starting session unity-greeter as user lightdm logging to /var/log/lightdm/x-0-greeter.log

and

[+1.78s] WARNING: Failed to open log file /var/log/lightdm/x-0-greeter.log: Permission denied

in the log but I can't find /var/log/x-0-greeter.log, there's only x-0.log and lightdm.log(which is generated by --debug option) in the folder. Maybe unity-greeter has some problem?

So, For short, these are what I want to ask.
1) Is it obvious that LXDM can't run Xfce? if not, Could you help me finding the reason why I can't?
2)Why can't I use LightDM?

Thank you for reading.

[onebir]

I also have this problem, and posted separately before finding this thread:
http://ubuntuforums.org/showthread.p...4#post11544334

(I don't recall being asked to choose a display manager during lubuntu or xubuntu desktop installation though.)

[MAFoElffen]

I also have this problem, and posted separately before finding this thread:
http://ubuntuforums.org/showthread.p...4#post11544334

(I don't recall being asked to choose a display manager during lubuntu or xubuntu desktop installation though.)

It is not a desktop problem. It is an Xauthority problem. I posted a fix for that in this post:
Reseting Authorities Profile For Logging into X

[onebir]

It is not a desktop problem. It is an Xauthory problem. I posted a fix for that in this post:
Reseting Authories Profile For Logging into X

Yes - thanks.
(I just posted here because I appeared to have the exact same problem.)