Why aren't I seeing my changes?
What do you mean 404 error?!?
Oh come ON, I just DID that!
How often are you working on something and are stuck trying to debug some irritation problem, only to discover after time that you've done something embarrassingly stupid? It's good to go through a checklist of "dumb" questions before spending an hour in the debugger or pouring over changesets.
Example:
- Is the computer plugged in? (classic tech support!)