I have seen that others have this issue like I do and after doing a great deal of research I have found a work-around. It is not a solution but it may make your life a little easier. This is a known “feature” of the 64 operating system – it has problems displaying the thumbnails created by 32 bit applications like Abode Acrobat. In order to see the thumb nails created by 32 bit applications you will need to use the 32 bit version of Windows Explore that is part of Windows Vista 64. To see how to do this and for more information pleases follow this link: http://support.microsoft.com/kb/895561#appliesto
I hope this helps. Take care guys.