Rrrrright, you guessed it – total system freeze in OS X. I can move the cursor around, but that’s it. The only remedy was doing a hard shutdown with the power button.
I would have been less annoyed by this if I was doing something unusual, like running an application I’m not normally running, or trying out new hardware, or really REALLY pushing the system, but I was just doing nothing in particular. And I would also be less annoyed if /var/log/system.log had any information at all about what happened.
Maybe RAM issues, or some other hardward problem? I’ll have to check. In any event – in addition to all the reasons stated above, I am doubly annoyed because I’m on OS X, which isn’t supposed to crash. Pfffft.