Error 4121: Prerequisite for this product is missing
Error 4121 occurs when attempting to install .NET 2.0:
One or more prerequisites for this product is missing.
This error occurs when Windows Installer 3.0 or higher is not installed or is damaged. The Microsoft .NET 2.0 Framework redistributable requires Windows Installer 3.0 or higher.
To resolve this error, download and install an updated version of the Windows Installer.