When windows based ATM machines crash, users can hit the taskbar, start menu, open paint and then make a stupid image to save as the background. What fun! Basically, this teaches ATM makers that they shouldn't use Windows for bank machines.
Implications - You really have to hand it to the clever person who figured out this inherent weakness in the ATM's operating system. As long as no sensitive or private data was accessed or fiddled with, this cheeky prank is hard to condemn. Let's just hope that the makers of the ATM take this playful lesson in stride and beef up the integrity of their product as a result.