I ran:
unity --reset
And got:
WARNING: Unity currently default profile, so switching to metacity while resetting the values
(metacity:3086): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3086): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3086): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3086): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
Checking if settings need to be migrated ...no
Checking if internal files need to be migrated ...no
Backend : gconf
Integration : true
Profile : unity
Adding plugins
Skipping upgrade com.canonical.unity.unity.01.upgrade
Skipping upgrade com.canonical.unity.unity.02.upgrade
Initializing core options...done
Initializing bailer options...done
Initializing detection options...done
Initializing composite options...done
Xlib: extension "GLX" missing on display ":0".
Xlib: extension "GLX" missing on display ":0".
Xlib: extension "GLX" missing on display ":0".
Compiz (opengl) - Fatal: glXCreateContext failed
Compiz (bailer) - Info: Ensuring a shell for your session
abdurahim@abdu-1:~$
(metacity:3151): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3151): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3151): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
(metacity:3151): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
Before being returned to the prompt.
gtk2-engines-pixbuf
as explained in this answer. – jcollado Feb 20 '12 at 07:37