Binary package hint: lastfm
When lastfm is running and is not minimized to the tray/notification area, a user request to logout (or shutdown) gets canceled, preventing the user from logging out.
In that case lastfm will get "closed" and moved to the notification area (not visible in Unity).
When lastfm is minimized to the notification area, a logout attempt will succeed. This might be the second one, or the first one, if lastfm was "minimized to the tray" already.
When using KDE/Kubuntu there's a notification about it (similar to "Last.fm canceled logout"), but when using Unity, there is no hint about why the logout does not work.
I do not know how this aborting process works, but I see no reason for why the user should be prevented from logging out just because music is being played in the background.
Reported in the upstream forum at: http://www.last.fm/forum/34905/_/678287
ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: lastfm 1:1.5.4.27091+dfsg-2ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Mon Apr 11 19:26:11 2011
ProcEnviron:
LANGUAGE=de_DE:en
PATH=(custom, user)
LANG=de_DE.UTF-8
SHELL=/bin/zsh
SourcePackage: lastfm
UpgradeStatus: Upgraded to natty on 2011-04-02 (9 days ago)
If you run last.fm and try to log out, you can't. When you hit log out, last.fm goes to tray and you do not log out. If you try to log out again (once last.fm is in the tray), then you are able to log out.