We haven't seen this issue before but we can get a better idea of what's happening behind the scenes by examining a couple of things from your Mac. Can you send the following to
support@splasm.com?
1. Your Audiobook Builder crash log. This is located at /Users/[your username here]/Library/Logs/CrashReporter/Audiobook Builder.crash.log.
2. A System Profiler report. You can create one of these reports by launching /Applications/Utilities/System Profiler.app and selecting Save from its File menu to save the report to your Desktop.