kernel failure while loading radeon module

[leechuck]

Since upgrading to 11.04 on my Acer 3820TG, I get kernel failures during startup when using switchable graphics. Using discrete graphics always works fine.
Eventually, I can reboot using switchable graphics as well, but usually not when on battery power.
I attach the syslog for a failed boot.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-8-generic 2.6.38-8.42
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: wl
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC271X Analog [ALC271X Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: leechuck 1405 F.... xfce4-volumed
 /dev/snd/controlC0: leechuck 1405 F.... xfce4-volumed
                      leechuck 1428 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf0600000 irq 43'
   Mixer name : 'Realtek ALC271X'
   Components : 'HDA:10ec0269,10250364,00100100'
   Controls : 18
   Simple ctrls : 10
Card1.Amixer.info:
 Card hw:1 'Generic'/'HD-Audio Generic at 0xcfedc000 irq 44'
   Mixer name : 'ATI R6xx HDMI'
   Components : 'HDA:1002aa01,00aa0100,00100200'
   Controls : 4
   Simple ctrls : 1
Card1.Amixer.values:
 Simple mixer control 'IEC958',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Date: Sat May 7 06:41:57 2011
HibernationDevice: RESUME=UUID=e598f1b7-86b7-4223-a1de-77906da64c93
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
Lsusb:
 Bus 002 Device 003: ID 04f2:b1d8 Chicony Electronics Co., Ltd
 Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Acer Aspire 3820
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-8-generic root=UUID=7c19f243-c795-49d6-a1ee-8ad2204d4a00 ro nosplash libata.force=noncq
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-8-generic N/A
 linux-backports-modules-2.6.38-8-generic N/A
 linux-firmware 1.52
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
StagingDrivers: brcm80211
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/02/2010
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: V1.17
dmi.board.asset.tag: No Asset Tag
dmi.board.name: Aspire 3820
dmi.board.vendor: Acer
dmi.board.version: V1.17
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.17
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrV1.17:bd09/02/2010:svnAcer:pnAspire3820:pvrV1.17:rvnAcer:rnAspire3820:rvrV1.17:cvnAcer:ct10:cvrV1.17:
dmi.product.name: Aspire 3820
dmi.product.version: V1.17
dmi.sys.vendor: Acer

[leechuck (leechuck)]

I forgot to add that booting the old 2.6.35 kernel works fine even with switchable graphics.