update manager crashes when try to update distribution

when i try to upgrade the distribution through update manager i receive an error message and i am not able to mantain ubuntu up-to-date.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.11
ProcVersionSignature: Ubuntu 3.5.0-41.64~precise1-generic 3.5.7.21
Uname: Linux 3.5.0-41-generic x86_64
NonfreeKernelModules: openafs fglrx
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Thu Mar 20 15:01:47 2014
DpkgHistoryLog.txt:

DpkgTerminalLog.txt:

GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1388513813
 com.ubuntu.update-manager window-height 685
 com.ubuntu.update-manager window-width 812
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)