I just suffered the same situation with wlx (wangliangxu) , sometimes it might restart X to gdm,or lost keyboard and mouse  and I have to hold the power button to shutdown my notebook.
Here are some details of my PC below.
Dell insprion N5010 with Ubuntu 12.04,Unity.(kernel 3.2.0.34)
ati HD5650 with amd-driver-installer-catalyst-12.10-x86.x86_64  compiled by myself.
And I still post some text from .xsession-errors
"(gnome-settings-daemon:12335): GnomeDesktop-WARNING **: GL_MAX_TEXTURE_SIZE helper quit unexpectedly

(gnome-settings-daemon:12335): color-plugin-WARNING **: failed to get edid: unable to get EDID for output
Backend     : gconf
Integration : true
Profile     : unity
Adding plugins
Initializing core options...done
Initializing composite options...done
** Message: applet now removed from the notification area
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
I/O warning : failed to load external entity "/home/wen/.compiz/session/1019c2abaa88a6cb55135462276869304600000122850033"
Initializing session options...done
Initializing gnomecompat options...done
Initializing animation options...done
Initializing fade options...done
** Message: using fallback from indicator to GtkStatusIcon
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:12356): GConf-CRITICAL **: gconf_client_add_dir: assertion `gconf_valid_key (dirname, NULL)' failed

(gnome-settings-daemon:12335): color-plugin-WARNING **: unable to get EDID for xrandr-LVDS: unable to get EDID for output
Initializing unityshell options...done
Setting Update "main_menu_key"
Setting Update "run_key"
Setting Update "show_hud"
** Message: moving back from GtkStatusIcon to indicator

** (zeitgeist-datahub:12990): WARNING **: recent-manager-provider.vala:133: Desktop file for "file:///home/wen/Downloads/Game" was not found, exec: shank-linux-120720110-1-bin, mime_type: inode/directory

(gnome-control-center:13015): background-cc-panel-WARNING **: Could not load /usr/share/themes/Adwaita/index.theme: No such file or directory

** (nautilus:12370): WARNING **: Error calling current_status: Method "current_status" with signature "" on interface "com.ubuntuone.SyncDaemon.Status" doesn't exist


** (nautilus:12370): CRITICAL **: syncdaemon_status_info_get_online: assertion `SYNCDAEMON_IS_STATUS_INFO (sinfo)' failed

(gnome-settings-daemon:12335): Gdk-WARNING **: gnome-settings-daemon: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(polkit-gnome-authentication-agent-1:12375): Gdk-WARNING **: polkit-gnome-authentication-agent-1: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.

gnome-session[12285]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.

gtk-window-decorator: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.0.

(gdu-notification-daemon:12570): Gdk-WARNING **: gdu-notification-daemon: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(nautilus:12370): Gdk-WARNING **: nautilus: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(gnome-fallback-mount-helper:12366): Gdk-WARNING **: gnome-fallback-mount-helper: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(gnome-screensaver:12989): Gdk-WARNING **: gnome-screensaver: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(telepathy-indicator:12972): Gdk-WARNING **: telepathy-indicator: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(bluetooth-applet:12368): Gdk-WARNING **: bluetooth-applet: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


(nm-applet:12369): Gdk-WARNING **: nm-applet: Fatal IO error 11 (Resource temporarily unavailable) on X server :2.


** (zeitgeist-datahub:12990): WARNING **: zeitgeist-datahub.vala:227: Unable to get name "org.gnome.zeitgeist.datahub" on the bus!
"



I hope this might be help!