Tiger has some genuine downright bugs. I guess this is to be expected, but man it does get old. The Panther upgrade was extremely smooth compared to this. Here's another honest-to-goodness bug I've found:
Under the Accounts Preference Pane you are no longer able to drag Login Items to define their startup order. According to an Apple Tiger support page you should be able to do this. Which in my mind means it's a bug.