Hi Chad,
This indicates that bulk_extractor has crashed for some reason, but a stack trace or log output would be required to know why. It's possible you've found a bug in bulk_extractor, but it's more likely you've encountered a flaw in the AFFLIB code.
I understand this may not be a newly acquired device, but in general you should not be using AFF as a disk image format - it is no longer being supported, and the original author has requested that people use E01 (via libewf) instead.
One quick check you could try is exporting the raw disk image via the affconvert command-line tool, running bulk_extractor on that, and seeing if you run into the same issue. If so, you should report it on the bulk_extractor user list (also a Google Group).
Regards,
Kam