There was a car carrying a hardware engineer, a systems analyst,
and a software engineer.
They were going down a steep hill when the brakes failed.
By a combination of the gearbox, the handbrake, and scraping the wheels
against the curb, they managed to just get the car stopped safely, and all
scrambled out.
"Right", said the hardware engineer, starting to disappear under
the car, "let's see if I can see what the problem is".
"I don't know", said the systems analyst, "I think we ought
to find a subject expert - like a braking engineer, and have him repair
it".
"Hang on", said the software engineer, "let's get back in
and see if it does it again".
Here is another version:
A mechanical engineer, an electrical engineer and a software engineer
are riding in an old Fiat. Suddenly the car coughs, backfires and breaks
down completely.
"It's probably a valve or a piston problem," volunteers the
mechanical engineer.
"Nonsense," says the electrical engineer. "It's mostly
a spark plug wire or the battery."
At which point the software engineer declares, "I know. Let's all
get out of the car and then get back in again!"