Most computers today do not have a true hard power switch, meaning that you flip it and the computer loses power. Most of them have some kind of electronics and software in the middle. The reason for this, ostensibly, is that Windows used to do really bad things if you just flipped the power off without letting the OS shut down first. So when all is well, pushing the power switch causes windows to shut down, and then the computer powers off.
The problem is that if the computer crashes bad enough, the power switch won't work, because the software or electronics behind it have crashed or locked up with everything else. Every few days I find myself in a situation where I am crawling on the floor having to pull the plug out of the wall to reboot, or, on a laptop, having to pull the plug and remove the battery.
Give me my hard power switch back!