Compiling a kernel and accidently didn't plug the AC adapter in. Battery went flat. Applied AC and rebooted. Messages about not doing a fsck for 30000-odd days and fsck launched. Logged in, but heaps of warnings about panel applets and Nautilus not being able to register with bonobo-activation-server. Left with a running X screen but no applications. Bugger.
So there's a couple of bugs here. Apple think it's OK to save some money and not provide a battery for the hardware clock.
GNOME thinks it's OK to crash if you start with a ridiculous system time. Or maybe they don't think this but also don't do any system testing.
The software culprit seems to be bonobo-activation-server. See Ubunutu bug #90923. It uses < rather than difftime(). A bug we'll see more of after 2038.