According to AV Interactive's article, TV-B-Gone is a key-ring attached ‘zapper’ that turns off all the TVs within its infra red range.
Don't allow this to happen to your digital signs. There are non-consumer displays such as the Philips Business Displays that will prevent this from happening. Using these displays with NetLink software, you have a secure solution and much more.
Alternatively, you can also use your imagination to block the infrared signal.