Comment 4 for bug 1427877

To increase the weirdness of the issue:
 - Volume slider in g-s top left menu works but the brightness slider doesn't work
 - If I go to Settings->Power the UI got frozen and it takes almost 20 seconds to show the panel. Find below the error output

(gnome-control-center.real:7317): GLib-CRITICAL **: g_variant_get_type: assertion 'value != NULL' failed

(gnome-control-center.real:7317): GLib-CRITICAL **: g_variant_type_is_subtype_of: assertion 'g_variant_type_check (type)' failed

(gnome-control-center.real:7317): GLib-CRITICAL **: g_variant_get_boolean: assertion 'g_variant_is_of_type (value, G_VARIANT_TYPE_BOOLEAN)' failed

(gnome-control-center.real:7317): GLib-CRITICAL **: g_variant_unref: assertion 'value != NULL' failed

Again if I reboot my computer those errors got fixed until some time passes.