uk only internet?

[Six Eyed Smily]

the network that is having trouble is configured as such: server running active directory with an adsl connection using RRAS to share the internet connection out amongst the network. however there is a problem.

the server itself can access all internet sites, however client machines seem only to be able to access certain sites, mostly those hosted in europe.
cleints can resolve the dns names of all sites, but pings and web retrievals time out. there is currently no firewall running on the server, the only things running are the aforementioned NAT, and other standard AD server stuff (QoS ect). as the server can access all sites, and cleitns can resolve addresses of all sites it is definately a problem with the server, however i cannot think what.

any ideas?

[Six Eyed Smily]

have tried using ICS instead of RRAS and still the same problem. am getting more and more confused, as nothing in the setup seems wrong