Product Key not valid - SharePoint Server 2010 RC

If you are installing SharePoint 2010 in the same machine when you had the beta versión may be you get the error that your Product Key is not valid when try to install the product.

The reason is due to the fact that the beta installation files are yet in the cache folder.

You need  go to the path C:\Users\Usuario Instalación\AppData\Local\Temp  and find a similar file like SharePoint Server Setup(2010020513575012B4...). If you open this file you can find de cache path, in my case C:\Program Files (x86)\MSECache\oserver2010.

You have to delete this folder to resolve the problem.