Unity/Compiz crashed at first login

Binary package hint: unity

This also happened during Natty Alpha 3 iso testing.
I wanted to try if Unity works, so I installed the properitary Nvidia drivers with Jockey, restartet, and tried to login.
But the first attempt was unsuccessful:
- Only the desktop wallpaper was shown, nothing else
- For at least 30 seconds, nothing visible happened on my screen
- But the noises from harddisk and cpu cooler indicated there was something going on in the background that used heavy cpu load.
- Then an information dialog appeared saying if I remember right that Compiz had crashed but there was not enough memory on my system (4 GB actually) to collect and report anything about this crash.
- The only possibility was to click 'ok', nothing else happend afterwards (still only the wallpaper was shown).

However, I could not reproduce this so far. Restarting the hanging desktop with 'sudo service gdm restart' worked well and two other attempts to login to Unity also worked like a charm.

The crash happened the first time when GDM(?) was trying to start Unity.

If I can provide additional informations for debugging, please let me know.

Kind regards,
Jan

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.6.0-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
Uname: Linux 2.6.38-5-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Thu Mar 3 16:56:08 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110302)
InstallationMedia_: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110302)
InstallationMedia__: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110302)
ProcEnviron:
 LANGUAGE=de_DE:en
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcVersionSignature_: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
ProcVersionSignature__: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
version.compiz: compiz 1:0.9.4-0ubuntu3
version.libdrm2: libdrm2 2.4.23-1ubuntu3
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.1~git20110215.cc1636b6-0ubuntu2
version.xserver-xorg: xserver-xorg 1:7.6~3ubuntu8
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-1ubuntu11
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu5