VAUGHNSC Hi Fab! I think Ive uncovered the cause of a bug that will cause the symtoms you describe and yes, it does affect more recent versions.
I'd like to mention for everyones benefit that when these issues arise, its exceedingly hard to get people to send over their backups (being personal data, not to mention HUGE). You might then understand why some of this behaviour is really hard to track down if it doesnt happen on my machines, my data :)
I expect to release another update on or before the end of this week (Thanksgiving 2008) which should go a long ways to ending the 'mysterious mid-scan quit'.