Hi,
The error you are reporting is a known issue that was introduced with the AutoCAD 2005-based applications, including the DWG Viewer that is included as part of the Autodesk DWF Composer product bundle. This issue has been resolved by the Service Packs that have recently been released for the AutoCAD 2005-based applications.
If you have AutoCAD 2005, AutoCAD LT 2005, or Autodesk Revit 6 installed, you should install the Service Pack 1 for these aplications to resolve the File Explorer crash problem:
(http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=4616541&linkID=2475323)
If you have the Autodesk DWG Viewer installed, you will need to apply the Autodesk DWG Viewer Service Pack 1 to resolve the issue: (http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=4864341&linkID=4083878)
I hope this information will help. Thank you for the feedback.
Best Regards,
Scott Lillibridge, Viewers QA
Autodesk Collaboration Services