Paul Emsley replied to this post with the suggestion that these problems normally happen when
guile-gtk is missing or somehow non-functional.
Paul suggested I download
http://www.ysbl.york.ac.uk/~emsley/software/binaries/nightlies/pre-release/coot-0.5-pre-1-
revision-786-binary-Linux-i386-fedora-5-python-gtk2.tar.gz
This release worked without modifications on my Ubuntu box.
Thank you Paul!