ThinkPad X201: intermittently powers off instead of suspending when closing the lid

I've been doing a lot of suspend/resume cycles of my laptop this week running precise, and had become convinced that I had a physical fault in my battery's connection because half the time after suspending my laptop and putting it in my bag, I would pull it back out to find that the machine was shut down (not hibernated - because hibernate works correctly for me and it wasn't resuming from hibernate on power on).

This morning I witnessed the power off directly and am convinced that this is a software bug, not a physically loose connection, because the laptop *started* to suspend, and then powered off.

Normally when suspending, the lights on the lid of the laptop are: solid green battery light, blinking green "night" light (crescent moon); then switching to solid green night light and no other lights on once the machine is suspended. What I saw this morning was: solid green battery light with blinking green night light; then solid green battery light and solid green night light; then all lights went out.

After rebooting, I find the following in /var/log/pm-suspend.log:

Fri Jan 13 06:20:49 CET 2012: performing suspend
Initial commandline parameters:
EOF

This is only intermittently reproducible, and I haven't been able to identify any variables on the desktop that account for the machine sometimes suspending and sometimes halting; so I think this is a kernel or upower bug.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: upower 0.9.15-1
ProcVersionSignature: Ubuntu 3.2.0-8.15-generic 3.2.0
Uname: Linux 3.2.0-8-generic x86_64
ApportVersion: 1.90-0ubuntu1
Architecture: amd64
Date: Fri Jan 13 08:19:43 2012
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: upower
UpgradeStatus: Upgraded to precise on 2011-11-08 (65 days ago)
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 1.90-0ubuntu1
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: vorlon 3195 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf2520000 irq 46'
   Mixer name : 'Intel IbexPeak HDMI'
   Components : 'HDA:14f15069,17aa2155,00100302 HDA:80862804,17aa21b5,00100000'
   Controls : 14
   Simple ctrls : 7
Card29.Amixer.info:
 Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw 6QHT30WW-1.11'
   Mixer name : 'ThinkPad EC 6QHT30WW-1.11'
   Components : ''
   Controls : 1
   Simple ctrls : 1
Card29.Amixer.values:
 Simple mixer control 'Console',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
DistroRelease: Ubuntu 12.04
HibernationDevice: RESUME=UUID=f6ab3c43-61b4-4af7-bf03-fa3b147a1de0
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root 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 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
MachineType: LENOVO 3249CTO
Package: linux (not installed)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.2.0-8-generic root=/dev/mapper/hostname-root ro pcie_aspm=force i915.i915_enable_rc6=1 crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-8.15-generic 3.2.0
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-8-generic N/A
 linux-backports-modules-3.2.0-8-generic N/A
 linux-firmware 1.67
StagingDrivers: mei
Tags: precise running-unity staging
Uname: Linux 3.2.0-8-generic x86_64
UpgradeStatus: Upgraded to precise on 2011-11-08 (65 days ago)
UserGroups: adm admin cdrom dialout libvirtd lpadmin mythtv plugdev sambashare src
WifiSyslog:

dmi.bios.date: 08/23/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 6QET52WW (1.22 )
dmi.board.name: 3249CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6QET52WW(1.22):bd08/23/2010:svnLENOVO:pn3249CTO:pvrThinkPadX201:rvnLENOVO:rn3249CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 3249CTO
dmi.product.version: ThinkPad X201
dmi.sys.vendor: LENOVO