aptitude is totally unusable due to rolling list of internal errors

[Michal Suchanek]

Errors like this keep rolling on the screen making the aptitude UI totally unusable.

 Internal error: the solver Install(upstart 1.4-0ubuntu7 <sysvinit-utils 2.88dsf-13.10ubuntu4.1 -S> {
upstart 0.6.6-3 upstart 0.6.6-4 upstart 0.9.7-1 upstart 1.3-0ubuntu10 upstart 1.3-0ubuntu11 upstart 1.4-0ubuntu7 upstart 1.4-0ubuntu7}>) of
a supposedly unresolved dependency is already installed in step 18034

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: aptitude 0.6.4-1ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-15.26-server 3.0.13
Uname: Linux 3.0.0-15-server x86_64
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
Date: Thu Feb 16 16:59:08 2012
InstallationMedia: Ubuntu-Server 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: aptitude
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[LaunchPeter (launchpeter)]

Same here. The resolver seems to wonder, that there are packages he selected to remove, that stay (since there are two versions of them in multiarch).
In my case I want to deinstall XFCE and this crazy resolver wants to offer a solution which would remove libc6.

This guy seems to have the same problem: http://<email address hidden>/msg967562.html