We can definitely help out but we'll need to gather some additional information. Would you be willing to send us a couple of things via email support to
support@splasm.com? If so, try to add something new in CheckBook like before and then, just after, here's what to get to us that'll be quite helpful:
1. A System Information report. You can create one by opening /Applications/Utilities/System Information.app (or System Profiler.app on an older OS), going to the File menu and clicking the Save... menu item. Save the report to your Desktop and attach it to the email.
2. Your system.log file, where the Mac and apps that misbehave log error—little clues for us. You can find this by clicking the Finder icon in your Dock, going to the Go menu at the top of your screen and using the Go to Folder... option to go to "/var/log" - without the quotes. The system.log file(s) will be in the window that appears. Both system.log and system.log.0.bz2 will cover it.
Once we have a look at that stuff, we should have a good chance of offering up a solution. Thanks!