Its not just dive computers
I once heard a very scary talk by a manufacturer of professional dive kit. He mentioned this kind of thing, but dive computers were actually one of the less scary parts.
The really scary stuff was rebreathers. These are bits of kit that take the air you breath out, scrub the CO2, add the oxygen back in, and let you breath it again. Advantages are much smaller tanks of compressed oxygen rather than air (8o% nitrogen), and no stream of noisy bubbles to scare the fish. The disadvantage is that if the oxygen replenishment fails you die before you realise there is anything amiss. One horror story among many: a device that reset itself to "off" when it got knocked.