Thank you for your question.
Please uninstall ADR 2009, and make sure the following two Autodesk Design Review folders are empty,
[%ProgramFile%]\Autodesk\Autodesk Design Review
[%CommonProgramFiles%]\Autodesk Shared\DWF Common
If there are files remaining, please delete the contents of those two folders.
Then install ADR 2010.
For more details, please refer to http://discussion.autodesk.com/forums/thread.jspa?threadID=726759&tstart=0
http://discussion.autodesk.com/forums/thread.jspa?threadID=725771&tstart=0
Please let me know if you have any further questions.
- Kenny
Kenny Guo
SW Engineer
Autodesk, Inc.