I'm having this problem.

Tried this:

$ unity --reset

This command hangs up on 'Setting Update "run_key"'

Also tried this:

$ ccmd

Unity plugin was disabled. I enabled it and rebooted. But still no luck.

Also tried this:

$ rm -rf ~/.config/compiz-1/compizconfig/*

$ rm -rf .compiz-1

$ sudo apt-get purge compizconfig-settings-manager

Nothing happened.

Also tried this:

$ sudo apt-get install --reinstall ubuntu-desktop



Reading package lists... Done

Building dependency tree       

Reading state information... Done

0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 0 not upgraded.

Need to get 0 B/3,928 B of archives.

After this operation, 0 B of additional disk space will be used.

(Reading database ... 164812 files and directories currently installed.)

Preparing to replace ubuntu-desktop 1.267 (using .../ubuntu-desktop_1.267_amd64.deb) ...

Unpacking replacement ubuntu-desktop ...

Setting up ubuntu-desktop (1.267) ...

It didn't work.

Any ideas?