Kudos to the Windows 7 team for building an awesome feedback loop.
Lately I had several tools fail when I tried to install them. Today the Windows 7 notification window gave me the solution. The crashes were not caused by the installers themselves but by the Customer Experience Improvement Program (CEIP). You know when you check the box to send anonymous feedback to Microsoft? Well it uses this system to send information about what you are installing and which options you selected.
This is useful information to us because it helps us to know what things people find useful. The solution to fix my installer problems for now is to disable this feature with a regkey entry. Windows 7 told me exactly what to do in step by step fashion. The most critical step is the following
In the Administrator: Command Prompt window, type or paste the following text at the prompt:
reg delete HKLM\SOFTWARE\Microsoft\SQMClient\Windows\DisabledSessions /va /f
Once I did this – the Silverlight installer worked without any problem at all!