Restoring from hibernate fails, goes to logon screen

In Ubuntu 10.10, hibernating seems to work, but when I come to restore it, it takes as long as it used to (a couple of minutes or so instead of 35 seconds for normal bootup) but at the end is back at the logon screen, having lost the session. I tried it first last night to this morning and then again this afternoon and both times it failed in this way. The debug messages that appear during normal (non-hibernated) bootup (the splash screen hasn't come up since 10.04 for some reason) don't show any abnormal failures and I can't spot anything unusual except that it doesn't work.

Sleep works properly, but when I need to unplug I need to shut down or hibernate due to a dodgy battery indicator on my laptop (HP 6710b), indicating "low battery" when fully charged (half an hour of power) and instantly waking it up again (and there doesn't appear to be an option for it in the BIOS).

In Ubuntu 9.10 (what I installed first) it worked fine normally but occasionally (one time in every ten or so) it would die for no apparent reason, locking up while shutting down. In Ubuntu 10.04 it was the same. Now it just seems to be failing silently (but taking all the normal - long - length of time).

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: linux-image-2.6.35-22-generic 2.6.35-22.35
Regression: Yes
Reproducible: No
ProcVersionSignature: Ubuntu 2.6.35-22.35-generic 2.6.35.4
Uname: Linux 2.6.35-22-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: chris 1650 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xe4804000 irq 47'
   Mixer name : 'Analog Devices AD1981'
   Components : 'HDA:11d41981,103c30c0,00100200 HDA:11c11040,103c1378,00100200'
   Controls : 11
   Simple ctrls : 9
Date: Thu Nov 4 23:17:36 2010
Frequency: Once a day.
HibernationDevice: RESUME=UUID=5202ab26-7608-405e-9747-10b519a9da6e
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
MachineType: Hewlett-Packard HP Compaq 6710b
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.35-22-generic root=UUID=0e76d302-a8c9-451c-9cbd-cf70ed7f4eb5 ro quiet splash
ProcEnviron:
 PATH=(custom, user)
 LANG=en_AU.utf8
 SHELL=/bin/bash
RelatedPackageVersions: linux-firmware 1.38
SourcePackage: linux
dmi.bios.date: 05/22/2008
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68DDU Ver. F.12
dmi.board.name: 30C0
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 71.2E
dmi.chassis.asset.tag: SGH81205DN
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68DDUVer.F.12:bd05/22/2008:svnHewlett-Packard:pnHPCompaq6710b:pvrF.12:rvnHewlett-Packard:rn30C0:rvrKBCVersion71.2E:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP Compaq 6710b
dmi.product.version: F.12
dmi.sys.vendor: Hewlett-Packard