Okay.
Have done several things and they have all slotted together fine.
Got one of my main testers to check his firewall settings. Norton helpline gave him some advice about configuring his firewall to enable site access without too many issues or security holes. I also checked the checkbox to disable the refer check. This seems to have done the trick for the others.
Thanks to all who chipped in with usefull info. You have all been very helpfull. I hope oneday to be able to return the favours (i'm fairly strong on Oracle).
Cheers
Barry
