Everywhere is already installed

Hello everybody.
I have a problem that won't let me install TCC.
Everything search service is already installed on my machine, so while installing TCC I choose "Do not install Everything Search".
Installation begins but it stops saying something like "Everything service could not be eliminated. You don't have privileges to uninstall system services" (I'm translating from italian).
I can only press Cancel.
Why does TCC installer try to uninstall Everything service? Is it a bug?
Thanks