screen unlocking issues -- gnome 3.8

[Pedro Francisco <pedrogfrancisco gmail com>]

I got the screen lock partially unlocked today again, requiring
killall -HUP gnome-shell to login.

Logs appear to show nothing useful.

«
Jun 19 18:18:15 s2 /etc/gdm/Xsession[980]: Window manager warning:
Buggy client sent a _NET_ACTIVE_WINDOW message with a timestamp of 0
for 0x2600025 (gnome-shel)
Jun 19 18:18:15 s2 /etc/gdm/Xsession[980]: Window manager warning:
meta_window_activate called by a pager with a 0 timestamp; the pager
needs to be fixed.
»

Any tips for better debugging?
--
Pedro