Hello Alan!

I'm afraid I need more information in order to help you. Could you please explain more clearly the issue, attach screanshots of it and eventually give me your website URL?
Thank you!

Hi Samantha,

                    I do not have a Apple Mac so unable to give Screen Shot,

http://www.alan-hayward.co.uk/create-enquiry.html

Thank you for the info and please excuse me for making you wait, I have been out of the office. The error they receive is dew to their browser, they need to update javascript, here's how to do it:

http://support.google.com/adsense/bin/answer.py?hl=it&answer=12654

Thank you i had guessed that may well be the answer but it had been happening more and more often and not sure if the problem was indeed the form.

Yes, that has to be what is causing them the issue. Please ask them to follow the procedure then let me know if I can help any futher.
Thank you!