When I was running Windows 7 Home Premium, Microsoft Office 2007 and Acrobat XI, I had this same problem and was able to fix it with the software from .
However, the PDF files were only visible in the Windows Explorer thumbnail view, but not its preview pane. After installing and updating the OS, MS Office, and Acrobat XI Pro, the common MS Office files displayed in the Windows Explorer thumbnail view and preview pane.
I recently upgraded my 64-bit OS from Windows 7 Home Premium to Windows 7 Ultimate and upgraded Microsoft Office from 2007 to 2010.