Sorry to ask a dumb question but are you sure that it is the Energy Saver Software that needs to be reinstalled?
If you have posted correctly and the message that you are getting is mentioning that "ess" needs to be reinstalled it could be a driver issue.
However assuming that it is the Energy Saver software causing the problem I would recommend re-installing it. I know that it seems stupid but, re-installing will actually make it easier to get rid of! Once you have re-installed and rebooted make sure you disable the Energy Saver Software before removing it. You should then be able to do this without any issues, through Control Panel/Programs/Uninstall a program. Once it has been uninstalled, reboot your PC and it should be fine.