Thanks for previous suggestions, and my apologies for violations of user-list etiquette. The output from the "why" command: > Unable to find a reason to install db5.1-util. I don't know what the package db5.1-util does. The "blocked update" led me to imagine that there was some serious bug or conflict with other packages. If this is not the case, my inept use of aptitude may have put some kind of hold on this package.