ubuntu 10.10 compiz background "fix" is turn up refresh rate
I expect others will see this problem with Ubuntu 10.10
I use compiz as the window manager and wallpaper manager. After a distribution upgrade from Ubuntu 10.04 to 10.10, I had the problem that compiz would no longer draw the wallpaper. I had a black screen, the background would not re-draw at all. Any time I opened a window and closed it, that window's image would remain drawn on the background. If I would drag a window, the small re-draws of the window frame would remain on the screen, like a sequence of "blurs" moving across the screen.
My hardware is old. 4 year old Dell Precision 670 with Nvidia Quadro FX 540
I hacked around quite a while, and eventually found a fix/workaround. In nvidia-settings, I have dual monitors running in Twinview and in the past I have always left the refresh rate set to "auto". Now, with Nvidia 260.19.06, it is necessary for me to manually specify 75mhz.
After that, compiz (suddenly!) starts drawing backgrounds as it is supposed to. I've re-started several times, and found each time that changing refresh from "Auto" to 75 is the magic bullet.