Originally Posted by Freebase Dali

You need to uninstall the previous versions of the .NET framework before downloading/installing the new version. Do:

1. Click Start, and then click Control Panel.
2. Double-click Add or Remove Programs.
3. Note each version of the .NET Framework that is already installed on the computer. Then, uninstall all the versions of the .NET Framework.
4. When you are prompted, restart the computer.
5. Proceed with the update to install the new .NET Framework version.

Let me know if that works.