The computer's disc drive was vibrating against
the top of the case. This wouldn't normally happen
but the monitor was sitting on top of the case and
the weight bowed the case in enough to touch the
top of the drive causing the sound. I told him
they would need to take the monitor off in order
for the sound to stop.

He said the computer has been making a terrible 
noise when the computer turns on. This has been 
doing this for 4 or 5 weeks.