Boot failure on battery power

Using a Lenovo Y450 Ideapad, first the 64-bit 11.04 ubuntu system would not boot on battery power, and upon the installation of the 32-bit 11.04, while system worked correctly for several days, today it showed the same behavior. I have the boot log relevant to the 32-bit system boot problem. Specifically:
1. Expected system to boot under battery power the same as the hard power boot.
2. What happened: 1st system hangs at the purple screen, no disk activity indicated. The upon rebooting, get a GRUB window, still under battery power. Rebooting hangs again under battery. Reboot with hard power works successfully.
Note that this has now happened under both the 32-bit and 64-bit 11.04 systems. I am reinstalling 10.04LTS to bypass this problem

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-8-generic-pae 2.6.38-8.42
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic-pae 2.6.38.2
Uname: Linux 2.6.38-8-generic-pae i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: i386
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: doug 1401 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf4800000 irq 50'
   Mixer name : 'Intel Cantiga HDMI'
   Components : 'HDA:10ec0269,17aa4000,00100004 HDA:80862802,80860101,00100000'
   Controls : 21
   Simple ctrls : 10
Date: Tue May 10 10:17:39 2011
HibernationDevice: RESUME=UUID=8a0660ff-f665-448a-a5d8-d11111df1f7e
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
MachineType: LENOVO IdeaPad Y450
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-8-generic-pae root=UUID=1c1c4f2d-7d63-499d-aa3d-1014989a1e0e ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-8-generic-pae N/A
 linux-backports-modules-2.6.38-8-generic-pae N/A
 linux-firmware 1.52
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/17/2009
dmi.bios.vendor: LENOVO
dmi.bios.version: 17CN35WW
dmi.board.name: KL1
dmi.board.vendor: LENOVO
dmi.board.version: Rev 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Rev 1.0
dmi.modalias: dmi:bvnLENOVO:bvr17CN35WW:bd09/17/2009:svnLENOVO:pnIdeaPadY450:pvrRev1.0:rvnLENOVO:rnKL1:rvrRev1.0:cvnLENOVO:ct10:cvrRev1.0:
dmi.product.name: IdeaPad Y450
dmi.product.version: Rev 1.0
dmi.sys.vendor: LENOVO