GDM won't unlock screen

[cothrige <cothrige@gmail.com>]

I recently installed Debian Testing on my laptop, an HP dv6-1355dx,
which had been running Ubuntu.  Once I got past the missing wireless
tools and drivers things have been pretty smooth.  However, there is an
oddity in GDM regarding screen locking which I cannot seem to figure
out.

With the default settings, using gnome-power-manager, whenever I close
the lid the computer suspends and the screen locks.  However, when I
open the screen it does not give me a password box or any such thing,
but rather the screen is just black.  This persists until I manually
switch to a console and back to F7 or F8, whichever is running X, and
only then will the expected password box appear.

I have looked through the seemingly related settings but can find
nothing which seems wrong or unexpected.  I have currently turned off
the screen-locking selection in the screensaver settings which keeps
things from locking up, in both ways, and so does not ask for a
password.  This is okay, though I would rather like to have things
working in the optimal way.

Thanks very much for any ideas.