The packaging process for the windows version of the agent has changed significantly in version 2.1.7.
If you have a prior version installed, please uninstall it manually from the Control Panel -> Uninstall a program and then install new one using the Windows install instructions. EU-hosted customers use this link instead.
Please, be on the safe side and do not forget to backup all config files.
There is no need to uninstall the previous version if it is greater than 2.1.6, just use the appropriate link above to install the new version.