Many users of Revit on Windows Vista have had issues related to thumbnail views of families in Windows Explorer. For some, like me, this issue solved itself at some point of time. For others, like Kjell Guttulsrød at boligPortalen, who asked me about this, salvation is close at hand:
Click Vista's Start button In the Search box, type Cmd Right-click on Command Prompt in the search result listing Click “Run as Administrator" Type regsvr32 "c:\program files\revit architecture2009\program\revitpreview.dll" The above "correctly" registers revitpreview dll.
Thanks to Mark Brandstatter for posting this at AUGI.
Please note that the path can differ from installation to installation.