Activating compiz messes up display

[viktor]

Binary package hint: compiz

After yesterday's updates to Lucid beta2 (64bit): kernel 2.6.32-20.29 i.e. before the actual upgrade to 2.6.32-20.30

So as to properly test Docky, I tried to launch compiz via System>Preferences>Display>Desktop Effects: Normal
it searched for 'Available drivers' for quite a few seconds then prompted to choose for Previous settings/Keep new.

Below, the "Desktop Effects" tab showed both "No Effects" and "Normal" selected.
On reopening this tab via the System menu it appears that compiz was not activated.

On reboot the display was messed up:
 * over the desktop, the cursor would be an X instead of the regular arrow
 * no titlebars, no window borders so it became really annoying to manage windows (esp. Firefox)
 * no window background/foreground priority: latest window would just stay front > extremely annoying

After today's updates and reboot into 2.6.32-20.30 I was able to reproduce this on first try. Going back to "Desktop Effects" fixed the issue, then again messed up.
Currently I'm only able to reproduce it while trying to set effects to Normal: the display is only messed up as described above for a while.

For the time being I don't know if this is related to my Nvidia (current) driver, Xserver or remaing Docky packages.