Curse Client uses the Internet Options from IE for retrieving and displaying the ads. You don't need any HOSTS file entries to block the ads, just add:
To the list of Restricted Sites. Doing so won't impact the ability to get the list of addons or update them, but it will prevent
from being downloaded and all the ad server scripts from being executed.
Code:
curseclient.curse.com
Code:
http://curseclient.curse.com/client-mpu-v4.html