Comment 28 for bug 389766

since post 22 i've had to removed/purged then reinstall some packages due to different issues. Doing this , ubuntu-desktop has been uninstalled too, then i've reinstalled it.

Looking the previous comments and having to say that my system has not these problems, i've checked synaptic to control which packagekit is installed:

i see that packagekit is no more installed, looking at ubuntu-desktop i'm surprised too that packagekit is not a dependency or a recommend package.