I've commented previously about my skepticism with theoretical Computer Science. My first personal, real encounter with it came in the form of a Real-Time Systems Course which has a heavy theoretical component.
My basic issue with it boils down to this: CS Theory predicts that some things will be possible when they're not possible on real machinery. It works in a world of algorithms and structures which have no real manifestation.
For example, Preemptive Earliest-Deadline-First scheduling can produce a schedule for any real-time task set that can be scheduled. But, in reality, preemptive EDF may have oodles of context switching which means that some task sets declared "feasible" cannot actually run on any real machines. I like to make things run, and this thing seems to be lying to me. See 2002 October 10 ammendment to this comment.
However, I've come to realize one big benefit from theoretical analysis: even though some things are possible in theory that are not possible in practice, nothing that's impossible in theory is going to be possible in practice. I.e., theoretical analysis is useful for telling us what we cannot do.
MacOS X -- maybe a little buggy
Averaged over the last two weeks, my MacOS X machine has hiccuped once every three days. Network activity stops and it won't start some programs. That's an annoyingly-high failure rate, and because there's no readily-available working shell (like a text console outside of the windowing environment) I haven't been able to analyze the running system to see what's happening.
While it's in this weird state, some programs won't start even in a running shell window. ping doesn't run; netstat does. 'ps' with no args does, 'ps auxw' won't run.
So I can't tell if it's just a kooky GUI thing (forgiveable, since GUIs are always kooky) or if it's something more fundamental (like a broken linker).