There are four engineers traveling in a car. One is a mechanical engineer, one a chemical engineer, one an electrical engineer and the other one an engineer from Microsoft.
 
The car breaks down.
 
"Sounds to me as if the pistons have seized. We'll have to strip down the engine before we can get the car working again," says the mechanical engineer.
 
 
"Well," says the chemical engineer, "it sounded to me as if the fuel might be contaminated. I think we should clear out the fuel system."
 
"I thought it might be a grounding problem," says the electrical engineer, "or maybe a faulty plug lead."
 
They all turn to the Microsoft engineer who has said nothing. They ask him, "What do you think?"
 
"Well, I think we should close all the windows, get out, get back in, and open the windows again."