Thanks for your prompt reply.
The problem is occurring in both IE 9 and Chrome, the only browsers I have checked so far.
It is a simple dropdown, here is the code:
public void AddChild(ICustomer child)
Child = child;
public IList<ICustomer> ChoicesAddChild(ICustomer child)
I did a bit of debugging and it is the api.updateChoices method in NakedObjects-Ajax.js which is making the call. I haven't quite figured out the purpose of this method yet.