This year I bought several new strings of Christmas lights, the fancy kind that flash multiple different light patterns. Several days after putting them up on the Christmas Tree, I noticed that one string was "stuck"; the lights did not flash. I thought it was somewhat strange that the lights would be "stuck", as I knew that the light controller was electronic, with no mechanical parts to get "stuck".
I unplugged and plugged in the lights, and pressed the button on the light controller box until the lights started working again.
I had walked a few steps away when it struck me what had just happened:
The light string was controlled by state-machine firmware. In other words, it was run by computer software.
I had just experienced a Christmas light firmware crash.
I had just rebooted my Christmas lights.