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https://www.myerrorsandmysolutions.com/windows-phone-software-development-kit-sdk-7-1-release-candidate-rc-windows-phone-7-sdk-visual-studio-setup-cannot-run-in-compatibility-mode-for-more-information-see-the-installing-sect/
Windows Phone Software Development Kit (SDK) 7.1 Release Candidate (RC) - "Windows Phone 7 SDK - Visual Studio setup cannot run in compatibility mode. For more information see the 'Installing' section in the Visual Studio Readme at "http://go.microsoft.com/fwlink/?LinkId=143397"."