Just want to let our Mac OS X 10.3.9 users know that we’re aware of the issue preventing it from launching properly. “Something” crept in at the last minute and zapped compatibility with 10.3.9. We’ll have it fixed soon but in the meantime, if you need to revert to CheckBook 1.8.1 you can download it at http://www.splasm.com/checkbook1x/downloads.html .