Openbox + Gnome OK in 32 bit, not 64 bit

[Scott V. McGuire]

Hi all,

I wonder if anyone has seen this or, even better, can suggest a fix.
My machine is set up to boot breezy i386 or AMD64.  In both, I've
tried setting openbox as my window manager using 'openbox --replace'.
In breezy i386, this works fine, but running AMD64, it interacts
strangely with something.  Every now and then when I minimize or
unminimize a window, I lose the desktop --- i.e. the wallpaper and
nautilus icons.  They seem to be replaced by a full screen,
undecorated, gray window complete with a scroll bar on the right.  In
addition, windows aren't represented in the workspace switcher
correctly --- they all show as if they're just thin slivers near the
top of the screen.

Anyone have a clue?

Thanks,

-- 
Scott V. McGuire