An unresolvable problem occurred while calculating the upgrade: The package 'ubuntu-desktop' is marked for removal but it is in the removal blacklist.
Aslan Gencer wrote on 2010-04-30: This workaround worked for me: Remove ubuntu-desktop with "apt-get remove ubuntu-desktop". (You'd probably need to do this while you are in a non-gnome desktop.) Then run the upgrade. ubuntu-desktop can be installed after the upgrade.