compizconfig-settings-manager causes hang

Binary package hint: compizconfig-settings-manager

I'm running an amd64 box with an NVIDIA 8400GS on gutsy, using the nvidia-glx standard drivers (I've also tried installing the nvidia-provided ones from their website).

I installed gutsy (upgrade from working feisty), and everything worked fine, with the box in compiz, etc., but after one restart (or X restart, I'm unclear which), I started getting a blank screen (or wallpaper-only) screen after gdm login (which proceeds normally). The upper and lower toolbars flash briefly, and then the wallpaper pops up, and although the mouse-pointer moves OK, there's no keyboard response (including Alt-Ctl-backspace). The machine responds fine to ssh, and I can restart X with 'sudo /etc/init.d/gdm restart' - with the same result.

After a great deal of investigation, it appears that I can install compiz by installing emerald, (with limited other packages) and run it with 'compiz --replace'and I get some effects, but no window decorations. Installing compizconfig-settings-manager causes the behaviour described.

I was hoping to be able to run gtk-window-manager to provide some window decorations, but this appears to be provided by compiz-gnome, which has compizconfig-settings-manager as a dependency.

Without compiz, the machine is virtually unusable: firefox takes ages to come up, amarok refuses to run, etc.

I'm willing to do a clean gutsy install if required, but don't want to lose this behaviour if it would be helpful to the bug-fixing team to replicate it.