I upgraded an existing 8.10 Ubuntu installation to 9.04 last week, and everything appeared to run fine initially. However no on boot I get a dialog box which says 'Not all updates can be installed'. Hitting the 'Partial Upgrade' button the list includes
Install libd4.6-java Install libd4.6-java-gcj Install liblrdf0 Upgrade acpid Upgrade libfreetype6 Upgrade liblucene2-java Upgrade update-manager Upgrade update-manager-core
If I then go with install the upgrade the dialog box disappears (after the permission to proceed password prompt) and nothing further happens until the next reboot, when I'm back to the partial upgrade prompt again.
Where should I look to find out what's going wrong and fix this