I was eventually able to guess that the problem was PHD2, but not before it had aborted and started warming up the camera back up. Aargh!
Software engineers really need to work on their failure modes. I'd never have gotten away with that when I was in the business.
Meaningless error messages? Yep - part of a software engineer's toolbag to piss off the client. I particularly like the ones that say something like "This program is about to crash". Why bother? If it's going to crash - crash. Don't tell me about it. I feel your pain. :sigh: