Q. How many software support operators does it take to change a light bulb?
A. One, but it takes an hour and a half to work out why the room is dark.
Q. How many PC technicians does it take to change a light bulb?
A. One, but it takes six weeks to change every piece of furniture in the house to isolate the fault, three months to wait for the replacement because it's not worth ordering just one bulb and then two weeks while the entire service centre staff take annual leave.