After update, metacity / compiz isn't started automatically anymore

After the updates of April 8th, on Lucid (10.04 beta), the window manager "metacity" is not being started at boot anymore. I have to start it manually, going in "Applications -> Terminal -> metacity&".

These updates also caused the visual effects to stop working. When I right click on the desktop, go in "System -> Preferences => Apparence" then click on Visual Effects tab and choose "Extra", the screen flickers but compiz is not enabled. If I click on the "Save parameters", this window hangs and I must kill it.

This using the Lucid Lynx beta (amd64) with all updates applied and "ubuntu-desktop" metapackage installed.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
Uname: Linux 2.6.32-19-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Sat Apr 10 10:25:00 2010
MachineType: ASUSTEK COMPUTER INC P5W DH Deluxe
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-19-generic root=UUID=8a3b1e0e-8412-4450-92ff-7eeaf6cdabe2 ro quiet splash
ProcEnviron:
 LANGUAGE=fr_CA:fr
 PATH=(custom, user)
 LANG=fr_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: xorg
Symptom: display
dmi.bios.date: 01/04/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 2504
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: P5W DH Deluxe
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2504:bd01/04/2008:svnASUSTEKCOMPUTERINC:pnP5WDHDeluxe:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP5WDHDeluxe:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: P5W DH Deluxe
dmi.product.version: System Version
dmi.sys.vendor: ASUSTEK COMPUTER INC
system:
 distro: Ubuntu
 codename: lucid
 architecture: x86_64
 kernel: 2.6.32-19-generic