This happened to me too, and I've noticed the screen flash on occasion. No graphics card.
12:03:06 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.gnome.ScreenSaver exited with status 1
12:03:06 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.gnome.ScreenSaver exited with status 1
12:02:59 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.ScreenSaver: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.gnome.ScreenSaver exited with status 1
12:02:58 PM gnome-session-b: Unrecoverable failure in required component org.gnome.Shell.desktop
This happened to me too, and I've noticed the screen flash on occasion. No graphics card.
12:03:06 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome. ScreenSaver: GDBus.Error: org.freedesktop .DBus.Error. Spawn.ChildExit ed: Process org.gnome. ScreenSaver exited with status 1 ScreenSaver: GDBus.Error: org.freedesktop .DBus.Error. Spawn.ChildExit ed: Process org.gnome. ScreenSaver exited with status 1 ScreenSaver: GDBus.Error: org.freedesktop .DBus.Error. Spawn.ChildExit ed: Process org.gnome. ScreenSaver exited with status 1 Shell.desktop
12:03:06 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.
12:02:59 PM gnome-session-b: CRITICAL: Unable to create a DBus proxy for GnomeScreensaver: Error calling StartServiceByName for org.gnome.
12:02:58 PM gnome-session-b: Unrecoverable failure in required component org.gnome.