What the error message said

Had you used the back button on your browser rather than our back button, before the error occurred?

How far did did you get into the booking (e.g. had you entered your name and address or got as far as entering your card details?)

The kind of browser you are using e.g. Internet Explorer version 6, Firefox 1.0, AOL

Is your PC a Windows PC or a Mac

Are you running a firewall, and have you tried a booking with the firewall off