Step 1. It would be super helpful if you could provide the following information at the beginning of your post:
Step 1. Follow Aaron Stebner's blog: http://blogs.msdn.com/astebner/archive/2007/08/01/4172276.aspx
Step 2. If this is a .NET Framework 3.5 install on Vista then you should run the following tool and post the output of the command: http://blogs.msdn.com/aaronru/archive/2007/11/29/net-framework-3-5-installation-validation-tool.aspx
Step 3. If this is a .NET Framework 3.5 isntall on Vista RTM then you should additionally try the following:
Run the following from an elevated command prompt
1. Winmgmt /verifyrepository
2. If the repository is reported as INCONSISTENT, run “Winmgmt /resetrepository” (if it fails because of service dependency, run “net stop winmgmt” and try again). If the repository is consistent, skip this step.
3. Do “mofcomp C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet.mof” to compile the failed mof.
If you feel the need to completely remove the .NET Framework and Visual Studio from your machines then you should follow the blog: http://blogs.msdn.com/aaronru/archive/2007/12/10/uninstalling-the-visual-studio-2008-rtm-or-rc.aspx
Thanks for taking the time to enhance our product.