By revert, I meant to my starting point, although I've got absolutely no idea why I'd want to, but your reply sounds like I can only work backwards through the nightlies...acceptable, because the most recent stable nightly is likely to be better than what I started with.
Since I'm taking advantage of the service, I'll report any bugs I encounter...if I can detail them accurately.
I'm now running the latest nightly, and it hasn't crashed in the 30 minutes since I installed it...a good sign.
I'll keep you and everybody posted.
Thanks for your help.