Échale un ojo a Javascript.
Código:
Me.CajaDeTexto.Attributtes.Add("onKeyPress","nuevoRegistro(event)")
Código PHP:
<script>
function nuevoRegistro(event)
{
var keyCode = event.keyCode ? event.keyCode : event.which ? event.which : event.charCode;
if (keyCode == 13) {
document.getElementById("btnNuevoRegistro").click();
}
</script>