^I don't understand that techie mumbo-jumbo and still can't understand why something never works when you need it most.
I believe it's all explained under Murphy's Law. With a health dose of Finagle's Law in there, too. Toss in little of von Moltke's paraphrased "No plan survives first contact with the enemy", and you'll have a pretty good idea of why somethings don't work when you need them most.
Plus, for all the technical aspects, IT is mostly magic and ritual with uncertain results at the best of times.