Ubuntu 13.04 mini: LXDE not working

[Framba]

I'm comparing 12.10 and 13.04.
/etc/pam.d/lxdm is equal (also the '@include common-session-noninteractive).
No differences with ck-list-session, while set has some:

diff set.lxdm.13.04.txt set.lxdm.12.10.txt 
10,12c10,12
< BASH_VERSINFO=([0]="4" [1]="2" [2]="45" [3]="1" [4]="release" [5]="x86_64-pc-linux-gnu")
< BASH_VERSION='4.2.45(1)-release'
< COLUMNS=128
---
> BASH_VERSINFO=([0]="4" [1]="2" [2]="37" [3]="1" [4]="release" [5]="x86_64-pc-linux-gnu")
> BASH_VERSION='4.2.37(1)-release'
> COLUMNS=100
18,19c18,19
< HISTFILESIZE=5000
< HISTSIZE=5000
---
> HISTFILESIZE=2000
> HISTSIZE=1000
29c29
< LINES=48
---
> LINES=37
39,41c39,40
< PIPESTATUS=([0]="0")
< PPID=863
< PROMPT_COMMAND='history -a'
---
> PIPESTATUS=([0]="1")
> PPID=747
49,50d47
< SSH_AGENT_PID=3385
< SSH_AUTH_SOCK=/tmp/ssh-jozqsA3384/agent.3384
54,56c51,53
< XDG_SESSION_COOKIE=6653bbde3e4a1159d6518b22518b7962-1368787107.532424-2038630725
< _=-lh
< __colormgr_commandlist=$'\n    create-device\n    create-profile\n    delete-device\n    delete-profile\n    device-add-profile\n    device-get-default-profile\n    device-get-profile-for-qualifier\n    device-inhibit\n    device-make-profile-default\n    device-set-kind\n    device-set-model\n    device-set-serial\n    device-set-vendor\n    device-set-enabled\n    find-device\n    find-device-by-property\n    find-profile\n    find-profile-by-filename\n    get-devices\n    get-devices-by-kind\n    get-profiles\n    get-sensor-reading\n    get-sensors\n    get-standard-space\n    profile-set-filename\n    profile-set-qualifier\n    sensor-lock\n    sensor-set-options\n    '
---
> XDG_SESSION_COOKIE=2735a62251d594061e8491e4519a0fa4-1369055538.889130-659026895
> _=']'
> __colormgr_commandlist=$'\n    create-device\n    create-profile\n    delete-device\n    delete-profile\n    device-add-profile\n    device-get-default-profile\n    device-get-profile-for-qualifier\n    device-inhibit\n    device-make-profile-default\n    device-set-kind\n    device-set-model\n    device-set-serial\n    device-set-vendor\n    find-device\n    find-device-by-property\n    find-profile\n    find-profile-by-filename\n    get-devices\n    get-devices-by-kind\n    get-profiles\n    get-sensor-reading\n    get-sensors\n    get-standard-space\n    profile-set-filename\n    profile-set-qualifier\n    sensor-lock\n    sensor-set-options\n    '
602,607d598
< }
< _desktop_file_validate () 
< { 
<     COMPRELY=();
<     cur=${COMP_WORDS[COMP_CWORD]};
<     _filedir '@(desktop)'

[Framba]

Maybe try to look at /usr/share/xsessions and see what is in there.

I don't know what to look for, but there are 4 files:
LXDE.desktop
openbox.desktop
openbox-gnome.desktop
openbox-kde.desktop

These files are identical in 12.10 and 13.04.