This post publicizes my latest finding that LCD monitor firmware has reached the level of unreliability of consumer-grade computer software, and therefore we even have to reboot our screens, every once in a while.
Just to make things crystal clear, power-cycling is turning a computer off, and then back on. It's also known as cold booting, and hard reset. It is different from resetting (warm-booting) a computer, because the equipment has to lose power completely, and not just undergo a complete software reload.
Today's desktop computers have removed the Reset button, so we have to resort to power-cycling the computer (usually by holding the power button for 4 seconds) any time it freezes completely. Warm-booting (slightly more gentle) is usually associated with software updates, and it's become a common but rare occurrence. Poor Windows users are forced into it once a month, by Microsoft's mandatory "you can say later, but turn your back for 5 minutes and I'll reboot your system" security updates.
So, cold reboots are associated with software failures. I learned to accept that as an inevitable consequence of operating systems being complex software (hundreds of millions of line of code) which are released based on time, not quality, to meet revenue goals.
Imagine my bedazzlement when I had to do the same thing to... my LCD monitor. I have a (reasonably old, granted) Dell E228WPFc (entry-level 22" widescreen, not HD). I tried to switch the DVI cable from my laptop to my Mac mini, and the monitor just wouldn't get out of sleep. After wasting 5 minutes wondering if any of the cables is broken, I yanked the power cable out of the monitor, waited for a second, then put it back in. And the screen lit up, and it worked.
Next time, I'll try power-cycling the screen earlier in the debugging process. And, as power-saving modes are implemented into more and more devices, I'll hope I don't step into an elevator which hangs getting out of sleep. Or in a car, for that matter.