Lots of them out there, apparently. Including the dreaded "Blue screen of Death" finally making an appearance in the Mac world.
I got lucky. Only one, and that easily enough resolved with five minutes research at the Apple Support page.
But it was a scary one. My administrator password got lost, and the fix involved booting into unix mode and typing things like:
dscl . -delete /Users/[username] AuthenticationAuthorityand ever since I learned about rm -r (deletes all files on the machine) I have been leery of mucking with the command-line interface.
But now TimeMachine is steadily plugging away backing up my irreplacables and I am enjoying my flip-view finder and all is good in the world.