X hangs when screen blanks on docked laptop

[Matthew Saltzman]

I have a Dell Latitude E6410 with nVidia graphics, using the nouveau
driver in F17 and gnome-shell.

When the machine is docked and using the remote display, all is well
until the screen blanker times out.  After that, I'm unable to wake the
screen up.  Opening the lid doesn't help (not too surprising, given that
the main screen is set to be off when the remote is attached); switching
to a VC doesn't help (which is surprising).  The keyboard still works,
so I can blindly switch to a VC and reboot, but it's not workable to
have to reboot after every 10 minutes of idle time.

I created a second userid and tried working with that, and the problem
does not recur there, so it apparently has something to do with the
configuration of my main userid.  I had at one point installed the
weather extension and the system monitor extension, but they were
problematic so I deleted them (before I tried the experiment with the
other userid).  That fixed a problem where the screen wouldn't wake up
even when undocked, but hasn't fixed this.

So any idea what I should look for in my userid's configuration files to
fix this?

TIA.
-- 
Matthew Saltzman
Clemson University Math Sciences
mjs AT clemson DOT edu