I came across this link while looking around to see if there were any other PDF quick view solutions.
http://pretentiousname.com/adobe_pdf_x64_fix/index.htmlFixes for 64-bit Adobe Reader preview handler and thumbnails[/url]
It brings up the registry changes as already discussed here but also goes into moire details of the preview handler problem than I've seen in other places. One thing mentioned was:
"If you have/had another PDF preview handler installed, such as FoxIt or PDF-XChange, then whichever handler was installed last will usually be the one which is used. Uninstalling preview handlers does not always put back the previous ones; instead, do a repair install or a re-install of the preview handler you wish to use so that it takes over the PDF preview handler registration. You can also do this by editing the PDF file-type in the registry. The tool above takes care of this and all the other issues so use that if you get stuck."
I've not yet tried any of the things discussed in this article. I found the link while surfing on my phone. Figured I'd post it here for comments first. There is no use in my mucking up something else if someone with more "under the hood" experience sees a reason any or all of this won't work. 3 years have passed since the article was written.
Might provide some new clues though. There are some links to IPreviewHandler topics. Above my head.
Like aurumdigitus mentioned above, all of the previous comments have been with regard to Adobe Reader and PDF-XChange
Viewer. What could be causing the problems with
Editor.? 
(Frustrated rhetorical question only)