Networks

I have a rule set for the internet users on my ISA server, where restricted internet access users has a schedule access time. The problem I'm having is that these restricted internet access users are not getting full access with the internet during their allowed time. Some websites open and some doesn't (e.g. www.google.com). But the unrestricted users don't get the problem of opening the sites (e.g. www.google.com)that the restricted users are having problem to open.