Shutting down

What do people expect from their computers when they've clicked the "Shut down" button?
I have asked around, wanting to get a more complete idea than my own, rather limited thinking.
The answers were, amazingly, more or less unanimous, along the lines of:
"I want my computer to power off."
The more technical savy friends of mine explained to me that the "powered off" state means that, _allthough_ the computer still uses some electrical energy, it is not 'active'. The CPU and memory are using no power at all, the disks are silent and no fans should be turning. The bit of electrical juice is taken by the motherboard in order to be able to 'detect' when you wish to power it on.

I apologize for that rather detailed description, but it is necessary to provide contrast to some of the experiences mentioned below.
So, what do the operating systems (or maybe their designers) think of the phrase "to power down"?
In most of unix and BSD clones, as well as the venerable z/OS from IBM, the idea behind the button (or command, as the case may be), is to _safely_ discontinue everything that the computer is doing and then with the aid of hardware to achieve the above mentioned "off state". The reason for 'safely' is that, presumably, you would like the computer to work at those tasks again in the future and do not fancy an idea of re-installing everything or correcting mistakes in data that come from sudden power loses. The IT industry invests massive amounts of money into insuring that power is not suddenly lost to big important computers.

But here comes a 'different' system. Windows (specifically the XP version).
I admit that it has occasionally happened to me that after commanding my Linux computer to shut down, it has failed to do so and stopped in the middle of that process. That usually signifies a large problem in the inner workings of the system, which bears investigation, or a large problem in the computer hardware, which is also a serious matter.
On the other hand, if everything worked perfectly and no hardware failures occured, the PC successfully shut down _EVERY SINGLE TIME I WANTED IT TO_. (Note the emphasis.)

Whereas, it is, I understand, a quite common occurence in Windows XP computers to simply.. stop in the middle of shutting down. Most of us have seen those nice "End Task" dialoges, which pop up when a stubborn program refuses to die quietly when ordered to.
The idea behind theese is that the OS is kind enough to wait for the task for a bit, and if it still refuses to cooperate, it will end the task 'forcibly'.
Naturally, that is not to be desired, as such scenarios lead to the afore-mentioned 'corrupted data'.
What confuses me, though, is that after the time limit is up (as indicated by the nice progress bar), the Windows OS asks you to kill the task, or abort shutting down. And it waits there, quite patiently.

Imagine a scenario: You are downloading images from the digital camera just before rushing off to your vacation. You click the shut down button and run off, confident in the knowledge that Windows will do the rest. Two months later you return home and find that: a) the computer has been on all this time and used up a not-inconsiderate amount of electricity, b) The image of that friendly little dialog is burned into your monitor, which you now have to replace and c) when you click any of the buttns in the dialog (after replacing the monitor), Windows continues shutting down, after which you need to turn your computer back on before you can start using it again.

Also, there is another thing:
If you have ever used a Windows computer in a networked environment with a file server, you will know about the so-called "offline files". It can be turned off, I understand, but in my experience, it never _stayed_ turned off for long.
The idea is that some files that you use often are copied to your computer and used from there, in order to decrease the load on your network.
The problem with this arrangement is (aside from conflicts and such that can appear when more people are changing the same files at the same time, the details of which I shall not mention here), that the files have to be uploaded back onto the server at some point. In Windows XP that happens when you turn your computer off.
If, for some reason, the connection is no longer available, the "synchronization dialog" will stop in confusion and tell you that it can't be done, waiting patiently for your click.

And, here is the third problem:
If the Windows XP in question has downloaded automatic updates and hasn't had time to bother you about installing them, it will do so before it shuts down. The idea seems fine on paper, but all too often it has happened that the updates failed and the computer got 'stuck' on the "installing updates - do not turn off your computer" screen.

Here are just three eventualities that result in your Windows XP not shutting down on their own, _AFTER_ you clicked the 'shut down' button. I imagine there are more out there which I haven't (luckily) come accross yet.

So, remember: Before going away from the computer, _WAIT_ for it to shut down completely, because you apparently _CAN'T_ trust Windows XP to do so on it's own every time.