I find that it's extremely finicky. Just now, I pressed Ctrl+O, and didn't
see any previews for Word documents, although I saw previews for other kinds
of files.
So, I started Excel, and found that *it* could preview Word files just fine.
I closed Excel, then started Word with the /a switch, and found that could
preview just fine.
I closed that copy of Word, then opened Word normally, and it suddenly was
showing previews of Word documents just fine.
Go figure. My guess is that all of the attempts shook something loose. I've
noticed this problem ever since Word 2007 was released. <sigh>
