I installed MS SQL Server Denali CTP3 (and its management studio) installed parallel to SQL Server 2008 R2, and everything works fine until I decided to uninstall Denali. The uninstallation of Denali was smooth and gave no error, however, after the uninstallation, MS SQL Server 2008 R2 Management Studio could not be launched. It didn’t give any error message and just didn’t launch at all. I had to reinstall MS SQL Server 2008 R2 to fix the error, and I could not just reinstall the Management Studio because it kept giving me installation error.

Bottom line, don’t install MS SQL Server “Denali” along with MS SQL Server 2008 R2.