I finally bit the bullet, and installed the three gnome ppas, after having nothing but problems on previous installs. This time everything seems to be working OK, except that I have a white window overlaying the desktop. During boot up, after logging in I can see the desktop background I chose before setting up the ppas, but just before the top panel shows, I can see the window open, and completely cover the desktop.

Has anyone else run into this, and if so what did you do to solve the problem?