can't solve a dependecy problem on apt-get

[Antonio Scarvaglieri]

I did an update and now when i try to install something it says me that i need to install a package because is needed by another package and i need to type apt-get -f install then when it tries to install this package it says that /usr/bin/dpkg returned an error(1)

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: libsane 1.0.22-7ubuntu1 [modified: lib/udev/rules.d/40-libsane.rules]
ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
Uname: Linux 3.2.0-27-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu11
AptOrdering:
 libsane: Install
 libsane: Configure
 ia32-libs-multiarch: Configure
 ia32-libs: Configure
Architecture: amd64
Date: Sun Aug 19 18:56:59 2012
DpkgHistoryLog:
 Start-Date: 2012-08-19 18:56:52
 Commandline: apt-get -f install
 Install: libsane:i386 (1.0.22-7ubuntu1, automatic)
ErrorMessage: './lib/udev/rules.d/40-libsane.rules' is different from the same file on the system
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
SourcePackage: sane-backends
Title: package libsane 1.0.22-7ubuntu1 [modified: lib/udev/rules.d/40-libsane.rules] failed to install/upgrade: './lib/udev/rules.d/40-libsane.rules' is different from the same file on the system
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.sane.d.dll.conf: 2012-05-25T15:15:13.715826