Ubuntu Ibex second monitor problem

[david-8uUts6sDVDvs2Lz0fTdYFQ at public.gmane.org (David Kramer)]

Right before the installfest we just had, I replaced Ubuntu 8.04 with
Ubuntu 8.10 on my Dell D620, which I use with my TV as a second 1380x768
monitor running a separate X screen 1 using NVidia's tool, the built-in
monitor being screen 0 at 1600x1050 (IIRC).  I also moved from KDE to
Gnome, in part because I had big problems with KDE[0], and in part
because I despise KDE 4.1[1].

I was having problems getting the dual screen setup to work, and I
actually brought the TV with me.  JABR found out the problem was that
the NVidia tool has to run as real root or the program fails silently to
write out the config file; sudo was not enough.  Easy fix.  Thanks.

I'm now facing a strange problem I can't even begin to theorize the
cause of.  It comes up with dual screens OK, and I get the wallpaper and
menus on my TV.  When I try to run a program on the TV screen from the
menus (like mythfrontend), it works.  If I run it from the icon on the
gnome panel (to the right of the menu), even though it's executing the
same command, I get a dialog box titled "Error" with absolutely nothing
in it.  Clicking on the X to close the window makes it flash, but it
doesn't go away.  At that point, neither menu or gnome panel icons work,
and top says gnome-panel is taking 100% CPU (which I believe, because
the fans go crazy.  But this is a Core2Duo, so I can still do other things).

I can kill 15 the gnome-panel process and everything works again, until
I click on another icon on the TV screen's gnome panel.

I guess this isn't a big critical problem, but it is unusual, and I
would like to know the cause to better understand X/Gnome/Dual screen.

Any clues?
Thanks.

[0] The task bar and menus wouldn't come up in consistent places, then
somehow I deleted them, and I couldn't get everything back the way it
was.  Also, it got confused over the screen size, and the desktop (the
whole desktop, including taskbar, etc) only covered part of the screen,
with the rest covered by the grey-and-white checker pattern you see in
GIMP when there's nothing there.  Lastly, it absolutely refused to put
even wallpaper and menus on the second monitor.  The mouse cursor would
appear on it, but that was it.

[1] I used the think all the ripping on KDE for eliminating
functionality and making the interface too simple and "Vista-like" was
unfounded.  Then I tried to work with it.  I was severely disappointed.