SBS 2008 UK websites

Hi

I have encountered a problem on a couple of servers (different locations) that have Windows SBS 2008 installed.

One location as Premium, the other Standard and the problem is common to both.

For no reason, users cannot gain access to websites ending .uk, .com are fine to resolve I run the connect to internet wizard and problem solved.

But this will only solve the problem for about 3-4 days, then it comes back.

Any ideas?