Hi Katy:
I am having the same problem too. I am tryying to install ArcGIS SilverlightViewer3_1_x64 on windows server 2008R2 64bit . I get an Install error " The process terminate unexpectedly". I have already installed ArcGIS for silverligt on windows 7 for test purposes and everything works fine.I am trying now to move my app to the server but can't install ArcGIS for silverligt.I have doubled to also ensure that all IIS web server components are installed.
Any help Please!!
Thanks.
Frankline
ONUCI