Since updating Apple's Developer Tools to Xcode 3.1.1, I am no longer able to work around a bug in Mac OS 10.3.9 which caused Bookdog to crash upon launch. Since Apple is no longer fixing non-security-related bugs in Mac OS 10.3, and since time is limited, I am no longer supporting Bookdog updates for Mac X OS 10.3.
If you have Mac OS X 10.3.9, you may download Bookdog 5.1.30. It works in Mac OS 10.3.9. Although no updates are planned, it has had its bugs well worked out over three years. Bookdog 5.1.30 was last updated on 2008 Sep 12.
Also, if you have Mac OS X 10.3.9, you should disable the automatic "Check for Updates when launching Bookdog", so that you are not bothered with update notifications any more. This picture shows how to do it:
