On a related theme, it could be a switch bounce, causing multiple electrical switch closures to be seen by the computer instead of the just the intended single 'click' you applied.
Try a plug-in mouse instead of the built-in track pad.
A surprisingly large number of computer faults can be caused by mechanical or electrical problems, rather than electronic or software faults.
Membrane switches - as used in thin lap-tops can misbehave - especially if liquid has been split. Has your friend spilt a cup of something over the keyboard ?
If so, see if the supplier will repair it under warranty, or claim under house insurance for accidental damage.