Upgrade From Ubuntu 12.04 to 14.04, fail with "An unresolvable problem occurred while calculating the upgrade."

[Donnie]

1. type "sudo update-manager -d" in the terminal.
2. E:错误，pkgProblemResolver::Resolve

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.13
ProcVersionSignature: Ubuntu 3.2.0-60.91-generic 3.2.55
Uname: Linux 3.2.0-60-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Sat Apr 19 18:58:59 2014
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1397904438
 com.ubuntu.update-manager window-height 500
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 12.04 "Precise" - Build amd64 LIVE Binary 20120426-19:46
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=zh_CN:
 TERM=xterm
 PATH=(custom, no user)
 LANG=zh_CN.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: Upgraded to precise on 2014-04-19 (0 days ago)
VarLogDistupgradeTermlog:

[Donnie (east000snake)]

 Removing ATI drivers and fightgear, the issue is solved.