package shorewall 4.4.21-1 failed to install/upgrade: subprocess installed pre-removal script returned error exit status 1

[hari1]

I was trying to remove shorewall from my system

ProblemType: Package
DistroRelease: Ubuntu 11.10
Package: shorewall 4.4.21-1
ProcVersionSignature: Ubuntu 3.0.0-9.15-generic 3.0.3
Uname: Linux 3.0.0-9-generic i686
NonfreeKernelModules: wl
AptOrdering: shorewall: Purge
Architecture: i386
Date: Sat Sep 3 21:09:09 2011
DpkgTerminalLog:
 Removing shorewall ...
 Stopping "Shorewall firewall": not done (check /var/log/shorewall-init.log).
 invoke-rc.d: initscript shorewall, action "stop" failed.
 dpkg: error processing shorewall (--purge):
  subprocess installed pre-removal script returned error exit status 1
ErrorMessage: subprocess installed pre-removal script returned error exit status 1
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
PackageArchitecture: all
SourcePackage: shorewall
Title: package shorewall 4.4.21-1 failed to install/upgrade: subprocess installed pre-removal script returned error exit status 1
UpgradeStatus: Upgraded to oneiric on 2011-09-03 (0 days ago)
mtime.conffile..etc.default.shorewall: 2011-08-27T23:50:21.475821
mtime.conffile..etc.shorewall.shorewall.conf: 2011-08-27T23:53:34.668780