This isn’t actually a bug as such, but it is about testing.

I used to be responsible for testing that the monthly Windows patches would not do any damage to the applications supported from my team.

One month I loaded the patches on to one of the test machines in the area and to my dismay the keyboard would not respond when I tried to test anything.

This was somewhat worrying so I rang the chap responsible for that set of applications and told him there was a problem with the patches and his applications.

He laughed and told me the problem was that I had not applied the hand brake.

He had to tell me that a few times because I assumed I had misheard him.
The normal laptop in our office does not have a hand brake.

However, this particular laptop was used for testing applications used by fork lift truck drivers. It is a very bad idea to use a laptop while driving a fork lift truck, so their laptops are interlocked so the keyboard only responds while the truck’s hand break is on. Unknown to me, this particular test laptop had a hand brake emulator.

There was no bug in the patches, but that day I was just a little late reporting that all was safe.