package postfix 2.9.3-2~12.04.3 failed to install/upgrade: subprocess installed post-installation script returned error exit status 75

i dont know it just keeps telling me there's a problem .. please fix it.

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: postfix 2.9.3-2~12.04.3
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
Uname: Linux 3.2.0-32-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.0.1-0ubuntu14
Architecture: amd64
Date: Sat Nov 3 12:07:28 2012
DpkgHistoryLog:
 Start-Date: 2012-11-03 12:05:46
 Commandline: aptdaemon role='role-commit-packages' sender=':1.78'
 Upgrade: gnome-power-manager:amd64 (3.4.0-0ubuntu1, 3.4.0-0ubuntu1.1), base-files:amd64 (6.5ubuntu6.2, 6.5ubuntu6.4), libgudev-1.0-0:amd64 (175-0ubuntu9.1, 175-0ubuntu9.2), libgudev-1.0-0:i386 (175-0ubuntu9.1, 175-0ubuntu9.2), udev:amd64 (175-0ubuntu9.1, 175-0ubuntu9.2), gir1.2-gudev-1.0:amd64 (175-0ubuntu9.1, 175-0ubuntu9.2), libudev0:amd64 (175-0ubuntu9.1, 175-0ubuntu9.2), libudev0:i386 (175-0ubuntu9.1, 175-0ubuntu9.2)
DuplicateSignature: InvalidHostOrDomain
ErrorMessage: subprocess installed post-installation script returned error exit status 75
EtcMailname: Gary.(null)
Hostname: Gary.(null)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
PostconfMydomain: localdomain
PostconfMyhostname: Gary.(null)
PostconfMyorigin: /etc/mailname
ResolvConf:
 # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
 # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
 nameserver 127.0.0.1
SourcePackage: postfix
Title: package postfix 2.9.3-2~12.04.3 failed to install/upgrade: subprocess installed post-installation script returned error exit status 75
UpgradeStatus: Upgraded to precise on 2012-04-26 (190 days ago)