Thanks for your replies.I have a work issued laptop with W7.I have limited admin status,unit setup by IT at HQ.I checked and Windows firewall is enabled.I ran the GRC test,all ports tested and got a perfect 'Trustealth' rating for 1st 1056 ports.I used the USB data stick in question for this test (and am using it now).
Don't know if it's relevant,but MS Forefront Client Security is running on the machine.I have no priveleges to see what it's doing.All I can do is see a list of applied updates which are pushed out over VPN from HQ.
Interesting.