This is the second time that my client has crashed when I logged off. Both times I used the "l" hotkey instead of clicking the button, so that might have something to do with it.

MacBook Pro, 2.2 Ghz, 2 GB RAM, OS X 10.5.4

Are you using TCS?
It might be a bug with the way TCS adds its button to the options dialog, but I thought ray fixed that.