Hello IanH,
Perhaps resetting the TCP/IP and Winsock may help. Try running the following commands using an elevated command prompt (run as administrator) and restart your system:
Netsh int ip reset
Netsh winsock reset
How to reset Internet Protocol (TCP/IP)
http://support.microsoft.com/kb/299357/en
How to repair TCP/IP and Winsock
http://www.speedguide.net/articles/how-to-repair-tcpip-and-winsock-1539
NOTE: These links are being offered for your convenience and should not be viewed as an endorsement by Intel of the content, products, or services offered there.