The problem started to happen when final version of ubuntu 12.04 was released. Through alpha-beta2 I didn't experience everything was ok. I didn't upgrade to the final release, I just reinstalled on a new partition. Since I experience this problem on Cinnamon, Unity 3D, gnome classic session (excluding the no effects version), and gnome 3, the problem lies in something else in Ubuntu 12.04. Maybe its xorg, compiz, or something that isn't working well with Nvidia drivers. I had version current and I'm using verison current updates. Results from running unity --reset When Unity 3D tries to load and manages not to have a segmentaion fault, it shows this at the end: "WARN unity.screeneffectframebufferobject ScreenEffectFramebufferObject.ccp:170 unsupported format WARN unity.gdk :0 compiz: Fatal IO error 11 (Resource Temporiraly unavailable) on X server 0. gtk-window-decorator: Fatal IO error 11 (Resource Temporiraly unavailable) on X server 0.0." I got this from running the command in terminal on Unity 2D: WARNING: Unity currently default profile, so switching to metacity while resetting the values unity-panel-service: no process found 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 Initializing core options...done compiz (core) - Warn: failed to receive ConfigureNotify event on 0x2000004 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x1400002 compiz (core) - Warn: failed to receive ConfigureNotify event on 0x1200002 Initializing composite options...done Initializing opengl options...done Initializing decor options...done Initializing vpswitch options...done Initializing snap options...done Initializing mousepoll options...done Initializing resize options...done Initializing place options...done Initializing move options...done Initializing wall options...done Initializing grid options...done Initializing session options...done Initializing gnomecompat options...done Initializing animation options...done Initializing fade options...done Initializing unitymtgrabhandles options...done Initializing workarounds options...done Initializing scale options...done compiz (expo) - Warn: failed to bind image to texture Initializing expo options...done Initializing ezoom options...done (compiz:8145): GConf-CRITICAL **: gconf_client_add_dir: assertion `gconf_valid_key (dirname, NULL)' failed Initializing unityshell options...done compiz (core) - Warn: unhandled ConfigureNotify on 0x3a00090! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x3a00093! compiz (core) - Warn: this should never happen. you should probably file a bug about this. compiz (core) - Warn: unhandled ConfigureNotify on 0x3a00096! compiz (core) - Warn: this should never happen. you should probably file a bug about this. WARN 2012-05-28 14:36:49 unity.libindicator :0 Desktop file '/usr/share/applications/google-chrome.desktop' is using a deprecated format for its actions that will be dropped soon. Initializing annotate options...done Initializing blur options...done Initializing clone options...done Initializing colorfilter options...done Initializing commands options...done Initializing cube options...done Initializing imgjpeg options...done Initializing kdecompat options...done Initializing mag options...done Initializing neg options...done Initializing obs options...done Initializing opacify options...done Initializing put options...done Initializing resizeinfo options...done Initializing ring options...done Initializing rotate options...done Initializing scaleaddon options...done Initializing screenshot options...done Initializing shift options...done Initializing staticswitcher options...done Initializing switcher options...done Initializing thumbnail options...done Initializing water options...done Initializing winrules options...done Initializing wobbly options...done ERROR 2012-05-28 14:36:52 unity.glib-gobject :0 g_object_unref: assertion `G_IS_OBJECT (object)' failed Setting Update "main_menu_key" Setting Update "run_key" Starting gtk-window-decorator Segmentation fault (core dumped)