vga_switcheroo does not work correctly

Hello,

I've tried to use vga_switcheroo as I've got an acer Timeline. It uses an ati card and an intel chipset.
In order to have vga_switcheroo working, I've modified my rc.local file like this :
sleep 10

chown jean-demange /sys/kernel/debug/vgaswitcheroo/switch || true
sleep 20

echo OFF > /sys/kernel/debug/vgaswitcheroo/switch || true
sleep 10
echo "eteignation de la carte" >> /var/log/rc.local_log
touch /var/log/rc.local_execute_avec_succes || true
exit 0

But sometimes (after a unpluging or plugin my computer, using sleep) the graphical session does not start correctly : the screen gets black and does not switch on again. I can access to a console with ctrl+alt+F1. I've put the dmesg.log produced when the computer does not start well.
In the console, when I try to reach /sys/kernel/debug/vgaswitcheroo/switch, nothing happen (eg : $sudo su then $cat /sys/kernel/debug/vgaswitcheroo/switch does nothing (the tty hang : it is not possible to do anything else)). But when the system correctly, with this command, I can see the state of both graphics cards.

Thanks.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-7-generic 2.6.38-7.39
Regression: No
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.38-7.39-generic 2.6.38
Uname: Linux 2.6.38-7-generic x86_64
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: ALC269 Analog [ALC269 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: jean-demange 1406 F.... pulseaudio
CRDA: Error: [Errno 2] Aucun fichier ou dossier de ce type
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xd4100000 irq 46'
   Mixer name : 'Realtek ALC269'
   Components : 'HDA:10ec0269,1025022b,00100004'
   Controls : 17
   Simple ctrls : 9
Card1.Amixer.info:
 Card hw:1 'HDMI'/'HDA ATI HDMI at 0xd4010000 irq 47'
   Mixer name : 'ATI R6xx HDMI'
   Components : 'HDA:1002aa01,00aa0100,00100100'
   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: Sun Apr 3 13:29:23 2011
HibernationDevice: RESUME=UUID=e774923d-3ee4-4015-86ce-3dac6e69a431
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110302)
MachineType: Acer Aspire 5810T
ProcEnviron:
 LANGUAGE=fr:en
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-7-generic root=UUID=eaa022b7-60bb-48a7-a7da-26ad3c9156fb ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-7-generic N/A
 linux-backports-modules-2.6.38-7-generic N/A
 linux-firmware 1.49
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/13/2010
dmi.bios.vendor: INSYDE
dmi.bios.version: V2.35
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Aspire 5810T
dmi.board.vendor: Acer
dmi.board.version: Base Board Version
dmi.chassis.type: 1
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnINSYDE:bvrV2.35:bd04/13/2010:svnAcer:pnAspire5810T:pvrV2.35:rvnAcer:rnAspire5810T:rvrBaseBoardVersion:cvnChassisManufacturer:ct1:cvrChassisVersion:
dmi.product.name: Aspire 5810T
dmi.product.version: V2.35
dmi.sys.vendor: Acer