Well first keep in mind that if the field is not editable, then it will not be rendered as a field to the browser. In other words, it will not have an INPUT tag – it will simply be text. Another suggestion would be to check all form events (e.g. WebQuerySave) to see what may be referencing the field. Although you did not mention it, I assume it must be a field that is somehow hidden from the user (otherwise it would be obvious whether the field was there on the form or not).
Thanks a lot for your reply…Well the field is a computed field which is not hidden from user. And the field has a question with four options as radio buttons…and all this is stored as html in the field. User selects one of the radio buttons as the answer and saves it…but im still unclear of the reason…can you please explain it ?