When the SDHelper (IE plugin) blocks something, it can tell you. Just use the "Spybot-S&D Configuration" menu item in the Tools menu of IE.
Other blocks (immunization: "Windows: Hosts file") would operate through the hosts file, in which case a notification isn't possible.
But blocking excite.com totally doesn't look like something it should do imho. Maybe it was just blocking the Excite cookie?