After trying a bunch of stuff, I eventually tried
unity --reset-icons
I get a message like:
Warning: no DISPLAY variable set, setting it to :0
(process:2053): dconf-warning **: failed to commit changes to dconf: Error
spawning command line 'dbus-launch --
autolaunch=d98463f4c1aa983d9fd6d0df22f42686 --binary-syntax --close-stderr':
Child process exited with code 1
compiz (core) - Info: Loading plugin: core
compiz (core) - Info: Starting plugin: core
Invalide MIT-MAGIC-COOKIE-1 keycompiz (core) - Fatal: Couldn't open display :0
compiz (core) - Info: Stopping plugin: (core)
compiz (core) - Info: Unloading plugin: (core)
and running
dconf reset -f /org/compiz
returns
error: Cannot autolaunch D-Bus without X11 $DISPLAY
It sounds like something is wrong with compiz but reinstalling it does nothing.
I've tried looking through previous threads like Ubuntu gets stuck in a login loop
I tried that first answer and it doesn't seem to be an issue of permissions on .Xauthority or /tmp
I tried other possibilities like updating Nvidia drivers but to no real avail.
I've tried reinstalling and reconfiguring lightdm and I've tried using gnome and lubuntu, which also get stuck in login loops but LXDE allows me to get to the desktop, though thats not much of a solution since it still seems video/graphics features aren't working with it.
