internal system error while refreshing with kpackagekit

[Lothar]

Binary package hint: kpackagekit

After pressing the "Refresh" button in kpackagekit I get an error dialog with the follwing details:

Error Type:
Error Value: coercing to Unicode: need string or buffer, exceptions.SystemError found
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2216, in
main()
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2213, in main
run(args, options.single)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 2175, in run
backend.dispatcher(args)
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 699, in dispatcher
self.dispatch_command(args[0], args[1:])
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 606, in dispatch_command
self.refresh_cache(force)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 202, in _locked_cache
func(*args, **kwargs)
File : /usr/share/PackageKit/helpers/apt/aptBackend.py, line 1498, in refresh_cache
format_string(error.message))
File : /usr/lib/python2.6/dist-packages/packagekit/backend.py, line 723, in format_string
txt = unicode(text, encoding, errors='replace')

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: kpackagekit 0.5.4-0ubuntu4
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
Architecture: amd64
Date: Mon Apr 19 22:56:05 2010
InstallationMedia: Kubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20100225)
ProcEnviron:
 LANGUAGE=
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: kpackagekit

[Lothar (lothar-tradescape)]

doing a refresh on the commandline works fine:

$ sudo aptitude update
[sudo] password for lothar:
Hit http://security.ubuntu.com lucid-security Release.gpg
Ign http://security.ubuntu.com/ubuntu/ lucid-security/main Translation-en_US
Hit http://archive.canonical.com lucid Release.gpg
Ign http://archive.canonical.com/ubuntu/ lucid/partner Translation-en_US
Get:1 http://us.archive.ubuntu.com lucid Release.gpg [189B]
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/main Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/restricted Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/universe Translation-en_US
Ign http://security.ubuntu.com/ubuntu/ lucid-security/multiverse Translation-en_US
Hit http://security.ubuntu.com lucid-security Release
Hit http://archive.canonical.com lucid Release
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/restricted Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/universe Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid/multiverse Translation-en_US
Hit http://us.archive.ubuntu.com lucid-updates Release.gpg
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/main Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/restricted Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/universe Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-updates/multiverse Translation-en_US
Hit http://security.ubuntu.com lucid-security/main Packages
Hit http://archive.canonical.com lucid/partner Packages
Hit http://us.archive.ubuntu.com lucid-proposed Release.gpg
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/restricted Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/main Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/multiverse Translation-en_US
Ign http://us.archive.ubuntu.com/ubuntu/ lucid-proposed/universe Translation-en_US
Hit http://security.ubuntu.com lucid-security/restricted Packages
Hit http://security.ubuntu.com lucid-security/main Sources
Hit http://s...

[Lothar (lothar-tradescape)]

I don't know if that is related, but I get a notification in the systray that says "Getting updates - Waiting for service to start" that sits there forever.