Drop down box ?!?!?

I have a combo box which I populate with items read from a database. The items in the box are not always the same, what is shown there depends on information in other text boxes. I have gotten so far as to when I choose whatever item in the box, except the first one, then they stay in there after the submition. I have a hidden text box which takes the value of the value of the combo box when it changes and the value is allways right, even when I choose the first item in the combo box. But if I choose the first item and submit the form the first item is not shown??? does anyone know why this is??? I hope you understand my problem... quite difficult to describe it...

Thank you in advance
Mundi

Computers and software @ EJS