save taskbar thumbnail previews - what does it do?

Okay, so I did a lot of searching and I thought I figured out what this option does (in the performance options within system properties). I thought it kept the thumbnail previews in the cache so when I hibernate or sleep, the previews will still be there. But that doesn't appear to be the case.

Usually, when I hibernate or sleep the computer, some of the previews don't show up and instead just shows the application's icon until I click on it and the preview gets saved again.

So basically, I see no difference between having this option checked vs not checked. Can anyone help?

Thanks!
(Specs are below, in case)

Thanks for the reply. Yeah, I saw your thread there but my assumption was that the main difference would be that if the preview had been cached once it wouldn't have to be reloaded again, but that doesn't seem to be the case. As I said, regardless of whether or not I have the option turned on or off, when I hibernate/sleep (sometimes, not all of the time), some previews don't show up and I have to open the window for it to show up.

So I really don't see any difference in keeping it on or off because when I hover over a window and it shows the preview, it seems to show it at the same speed both times.
Could you give me any more detail?
Thank you

The windows are open. Come on, gimmie some credit :P
And I do have a pretty fast system as you can see from my specs.
This is what I mean when I say it doesn't display the thumbnail previews regardless of having the box checked or not.

Is it an Adobe Reader issue as well? Cuz I've had it happen there as well.

I haven't seen it happen in Notepad, but I have noticed it in Microsoft Word.