A while back, some folks I know were talking about the difference between someone who is a computer administrator and someone who is a systems administrator. Basically concentrating on the differences in thinking necessary when you move from dealing only with a single, isolated machine to dealing with multiple systems, with parts that can interact in subtle and non-trivial ways.
I think I've found a concrete example that demonstrates well this difference, and I found it this morning in the restroom just down the hall from my office. A while back, watersaving faucets were installed in this restroom, which is a generally a good thing. The hot water source for this restroom, however, appears to be somewhere in the vicinity of Toledo, and there does not appear to be any pipe insulation. So, you either sit there for a long period of time, waiting for something resembling warm water to appear (which, of course, totally negates the water-saving part of the faucet), or you wash your hands with clean, cool water. I usually opt for the later, and to add insult to injury, every time I do this I read the sign on the mirror telling me that in order to help prevent the spread of The Oink, I should wash my hands with plenty of soap and warm water.
A concrete example, I think, of how individual actions, which alone make sense, fail in a systems context.