when I shutdown, it doesn't shut down; I have to hold the power button

[linlin]

Dell inspiron 1525, using Wubi, won't shut down, says something about loops...

ProblemType: KernelOops
Annotation: Your system might become unstable now and might need to be restarted.
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: yjli 1701 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xfe9fc000 irq 21'
   Mixer name : 'SigmaTel STAC9228'
   Components : 'HDA:14f12c06,14f1000f,00100000 HDA:10951392,10280242,00100000 HDA:83847616,10280242,00100201'
   Controls : 33
   Simple ctrls : 20
Date: Wed Nov 4 21:04:55 2009
DistroRelease: Ubuntu 9.10
Failure: oops
MachineType: Dell Inc. Inspiron 1525
Package: linux-image-2.6.31-14-generic 2.6.31-14.48
ProcCmdLine: root=UUID=5E0C4B8B0C4B5CE1 loop=/hostname/disks/root.disk ro quiet splash
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
RelatedPackageVersions:
 linux-backports-modules-2.6.31-14-generic N/A
 linux-firmware 1.24
SourcePackage: linux
Tags: kernel-oops
Title: BUG: scheduling while atomic: swapper/0/0x10010000
Uname: Linux 2.6.31-14-generic x86_64
WpaSupplicantLog:

dmi.bios.date: 01/07/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A08
dmi.board.name: 0WP007
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA08:bd01/07/2008:svnDellInc.:pnInspiron1525:pvr:rvnDellInc.:rn0WP007:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Inspiron 1525
dmi.sys.vendor: Dell Inc.