Enter Key Suddenly not posting

Hello all,
I've got a strange problem with my login page. Here are the facts:
The enter key submits fine in visual studio The enter key submits fine on the dev server. The enter key used to subtmit fine on the production server. I can replicate the issue until the cows come home. <div>Here is the code:</div> <div></div> <div><%@ Page Language="C#" MasterPageFile="~/MasterPages/Main.master" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" Title="Login" ValidateRequest="false" EnableEventValidation="false" %></div> <div></div> <div></div> <div><asp:Panel runat="server" DefaultButton="lnkLogin ...