impossible upgrade for old version to new version of ubuntu

[ncharpen]

"An unresolvable problem occurred while calculating the upgrade:
Le paquet « postgresql-plperl-8.4 » est marqué pour suppression mais il est dans la liste noire des suppressions.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu"

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: update-manager 1:0.150.5.1
ProcVersionSignature: Ubuntu 2.6.38-13.52-generic 2.6.38.8
Uname: Linux 2.6.38-13-generic i686
NonfreeKernelModules: wl
Architecture: i386
Date: Thu Dec 15 22:23:53 2011
GConfNonDefault:
 /apps/update-manager/check_new_release_ignore=
 /apps/update-manager/first_run=false
 /apps/update-manager/window_size=(510,546)
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=fr_FR:en
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: Upgraded to natty on 2011-12-15 (0 days ago)
VarLogDistupgradeApttermlog:

VarLogDistupgradeHistorylog:

VarLogDistupgradeSystemstatetargz:

VarLogDistupgradeTermlog:

[RedSingularity (redsingularity)]

Sorry for the delay. What the output of:

apt-cache policy libpanel-applet-3-0
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[Launchpad Janitor (janitor)]

[Expired for update-manager (Ubuntu) because there has been no activity for 60 days.]