Kernel Oops - BUG: unable to handle kernel paging request at 16ccfc59; EIP is at ttm_mem_io_lock+0x8/0x30 [ttm]

appeared randomly

ProblemType: KernelOops
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-7-generic 2.6.38-7.39
Regression: Yes
Reproducible: No
ProcVersionSignature: Ubuntu 2.6.38-7.39-generic 2.6.38
Uname: Linux 2.6.38-7-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Annotation: Your system might become unstable now and might need to be restarted.
Architecture: i386
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: SB [HDA ATI SB], device 0: ALC269VB Analog [ALC269VB Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: filip 1641 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'SB'/'HDA ATI SB at 0xfdcf8000 irq 16'
   Mixer name : 'Realtek ALC269VB'
   Components : 'HDA:10ec0269,1462106e,00100100'
   Controls : 13
   Simple ctrls : 8
Card1.Amixer.info:
 Card hw:1 'HDMI'/'HDA ATI HDMI at 0xfdee8000 irq 19'
   Mixer name : 'ATI RS690/780 HDMI'
   Components : 'HDA:1002791a,00791a00,00100000'
   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: Mon Apr 4 23:45:45 2011
Failure: oops
Frequency: This has only happened once.
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110202)
Lsusb:
 Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 002 Device 002: ID 5986:02c1 Acer, Inc
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Micro-Star International MS-168B
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-7-generic root=UUID=c652bc0f-f0c6-43f9-994d-6f03365193e0 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
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
StagingDrivers: rt2860sta
Title: [STAGING]
UpgradeStatus: Upgraded to natty on 2011-03-25 (10 days ago)
WifiSyslog:

dmi.bios.date: 08/12/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: A168BAMS Ver1.09
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: MS-168B
dmi.board.vendor: msi
dmi.board.version: Ver 1.000
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 10
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrA168BAMSVer1.09:bd08/12/2010:svnMicro-StarInternational:pnMS-168B:pvrVer1.000:rvnmsi:rnMS-168B:rvrVer1.000:cvnToBeFilledByO.E.M.:ct10:cvrToBeFilledByO.E.M.:
dmi.product.name: MS-168B
dmi.product.version: Ver 1.000
dmi.sys.vendor: Micro-Star International