Screensaver fails to activate -- appears an event is cancelling it

[Noel J. Bergman]

Binary package hint: gnome-screensaver

Host:
   Thinkpad T61p 6457-7WU
   nVidia FX570M
   Intrepid with all current updates, including
     nvidia-glx-173 173.14.12-1-0ubuntu2
     gnome-screensaver 2.23.3-0ubuntu2
     xscreensaver-gl 5.05-1ubuntu2

After the configured period of time, the screen will dim, then go completely black, but then instead of the screensaver activiating, the screen will go back to normal immediately as if some event arrived to cancel the screensaver. To further support the hypothesis, if I enable locking, as soon as the screen goes blank, instead of the screensaver activating, the unlock dialog is presented.

[Noel J. Bergman (noeljb)]

Also, after cancelling the unlock dialog, the screensaver will activate as expected.