That particular error can come up in Audiobook Builder for a variety of reasons. We can surely help get you going again, but we'll need to gather some more info about what exactly's happening on behind-the-scenes. Specifically, seeing a System Information report generated just after the issue occurs would be quite helpful since this'll show logged background processes on your Mac. So, if you're willing to send one of those, get Audiobook Builder to present the same error message and then just after launch 'System Information.app' (or 'System Profiler.app' on older OSes) from your Applications/Utilities folder. Then, use the Save option under the File menu—attach the resulting file to a message to
support@splasm.com and we'll have a look.