I'm guessing somewhat here, but I suspect you're using the
Validating[
^] event to validate your textbox, and that's preventing you from clicking on your "exit" button unless you've entered a valid value.
If that's the case, you need to set the
CausesValidation[
^] property on the "exit" button to
False
. That way, the
Validating
event will not fire when the button is clicked.