OK thanks for confirming what I thought it seemed to be, happy nope I have one browser working on this machine.
1. Already done it
2. that too
3. Have listed the machines it only effects the one where the site was loaded.
This final fix seems to resolve the problem in Opera but Safari (used for the install), Chrome and Firefox still not working. An interesting problem, I could understand it effecting the browser that was used to install or update the site but not the others on the same machine.
I will report what happens when the computer is restarted as this may have an overall clearing effect.
