This is one of those quirky problems where so many little interactions between programs are hard to track.
This thread: http://www.adobeforums.com/webx/.3c062187
The bottom of the thread almost implies that the cause of the problem is that I am running 64bit windows and the PDF preview generator is a 32bit app, but the thread itself is written by a person with problems on 32bit vista.
I’m not sure what is stopping these from being generated automatically. Thumbnail previews are all enabled in vista.
The thumbnails are generated if I open up acrobat 8, then use the open dialogue and sit on a page as the thumbnails load. After that, explorer shows the previews generated by acrobat 8.
That’s a solution I will gladly take over NOTHING. but far far far from ideal.
I’m going to try enabling all of the services that I disabled in my fresh install. Maybe one of those took care of it.