The relevant parts of lightdm.log show:
[+16.34s] DEBUG: Session pid=5887: Running command /usr/sbin/lightdm-session gnome-session --session=ubuntu [+16.34s] DEBUG: Creating shared data directory /var/lib/lightdm-data/richard [+16.34s] DEBUG: Session pid=5887: Logging to .xsession-errors [+16.37s] DEBUG: Activating VT 7 [+16.37s] DEBUG: Activating login1 session c28 [+16.98s] DEBUG: Session pid=5887: Exited with return value 0
Which is showing that the session has immediately ended as soon as you logged in. You might be able to better debug this by checking ~/richard/.xsession-errors after this occurs.
The relevant parts of lightdm.log show:
[+16.34s] DEBUG: Session pid=5887: Running command /usr/sbin/ lightdm- session gnome-session --session=ubuntu lightdm- data/richard
[+16.34s] DEBUG: Creating shared data directory /var/lib/
[+16.34s] DEBUG: Session pid=5887: Logging to .xsession-errors
[+16.37s] DEBUG: Activating VT 7
[+16.37s] DEBUG: Activating login1 session c28
[+16.98s] DEBUG: Session pid=5887: Exited with return value 0
Which is showing that the session has immediately ended as soon as you logged in. You might be able to better debug this by checking ~/richard/ .xsession- errors after this occurs.