keyboard handler problem

i have a text box, where user should enter an id. If he enters an invalid id and presses ENTER, i would like to offer him a form with list of valid id's. On that form i have a keypress sub on an active text box (if ENTER is pressed the current id is returned to first form). The problem is that when i enter invalid id and press ENTER on the first form, the second form appears and disappears and returns the firs id of the list. Seems like the same ENTER is interpreted (and reacted upon) by both forms. How can i avoid this?

How about this ?