agCoreService is not a Microsoft-supplied program, and not a standard
part of a Windows installation. I suspect that it belongs to software
produced by AG Interactive, a subsidiary of the America Greetings
Corporation:
You probably have (perhaps unwittingly) some AG software installed, such
as the Kiwee Toolbar. If so, you might need to ask AG Interactive what
their software is doing, dialling home? And/or, if its an issue,
uninstall the software from your machine; that should remove the
agCoreService service.