If you just ran the setup, the install engine takes a few seconds at the end of the installation to clean up. During this time Ikernel.exe (the install engine file) is running in memory from a previous process. That is why you are not allowed to launch another setup. Waiting a few seconds and running the setup again should resolve this. Check and make sure Ikernel.exe is not in memory. If it is, and no setup is running at the time, end that task and restart the system.