brightness issue. brightness decreases by itself

Binary package hint: unity

15 to 20 minutes after increasing the brightness, the brightness automatically decreases to something that is quite difficult to read the screen. this happened at least 3 times in the last hour.

am using 11.04 on trial basis on a toshiba nb305 netbook.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.8.10-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,unitymtgrabhandles,scale,session,unityshell]
CompositorRunning: compiz
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1024x600
 edid-base64: AP///////wBMo05UAAAAAAASAQOAFg14CoWVmVdPjyYhUFQAAAABAQEBAQEBAQEBAQEBAQEBGxUAQEFYRiAYiDYA330AAAAZAAAADwAAAAAAAAAAAB60AnQAAAAA/gBTQU1TVU5HCiAgICAgAAAA/gAxMDFOVDAyLVQwMQogAOA=
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
Date: Mon May 16 19:28:31 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
GdmLog1:

GdmLog2:

GraphicsCard:
 Intel Corporation N10 Family Integrated Graphics Controller [8086:a011] (prog-if 00 [VGA controller])
   Subsystem: Toshiba America Info Systems Device [1179:ff30]
   Subsystem: Toshiba America Info Systems Device [1179:ff30]
LiveMediaBuild: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
LiveMediaBuild_: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
LiveMediaBuild__: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
MachineType: TOSHIBA TOSHIBA NB305
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz noprompt cdrom-detect/try-usb=true file=/cdrom/preseed/hostname.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
ProcVersionSignature_: Ubuntu 2.6.38-8.42-generic 2.6.38.2
ProcVersionSignature__: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Renderer: Unknown
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/03/2010
dmi.bios.vendor: TOSHIBA
dmi.bios.version: V1.70
dmi.board.name: NPVAA
dmi.board.vendor: TOSHIBA
dmi.board.version: 1.00
dmi.chassis.asset.tag: *
dmi.chassis.type: 10
dmi.chassis.vendor: TOSHIBA
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnTOSHIBA:bvrV1.70:bd06/03/2010:svnTOSHIBA:pnTOSHIBANB305:pvrPLL3AC-00F014:rvnTOSHIBA:rnNPVAA:rvr1.00:cvnTOSHIBA:ct10:cvrN/A:
dmi.product.name: TOSHIBA NB305
dmi.product.version: PLL3AC-00F014
dmi.sys.vendor: TOSHIBA
version.compiz: compiz 1:0.9.4+bzr20110415-0ubuntu2
version.libdrm2: libdrm2 2.4.23-1ubuntu6
version.libgl1-mesa-dri: libgl1-mesa-dri 7.10.2-0ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.2-0ubuntu2
version.xserver-xorg: xserver-xorg 1:7.6+4ubuntu3
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu7
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu7