JSP not working with Windows 7

The below JSP (using Tomcat 6.0.24) to fetch Intranet Username has
always worked on Windows XP with IE.
Now that we upgraded to Windows 7 it no longer works. It now responds
with IE generic message Page not found. Tomcat logs doesnt show any
information or error messages.

Anything I can change to make it work using Windows 7?

<%@ page import="sun.misc.BASE64Encoder,java.util.regex.*" %>
<p><h1>Network Windows USERNAME without any login (ie)</h1></p>
<%
String auth = request.getHeader("Authorization");
if (auth == null) {
        response.setStatus(response.SC_UNAUTHORIZED);
        response.setHeader("WWW-Authenticate", "NTLM");
        return;
}
if (auth.startsWith("NTLM ")) {
        byte[] msg = new
sun.misc.BASE64Decoder().decodeBuffer(auth.substring(5));
        int off = 0, length, offset;
        String s;

        if (msg[8] == 1) {
            off = 18;

            byte z = 0;
            byte[] msg1 = {(byte)'N', (byte)'T', (byte)'L', (byte)'M',
(byte)'S',
                            (byte)'S', (byte)'P', z,
                            (byte)2, z, z, z, z, z, z, z,
                            (byte)40, z, z, z, (byte)1, (byte)130, z,
z,
                            z, (byte)2, (byte)2, (byte)2, z, z, z,
z, //
                            z, z, z, z, z, z, z, z};
            //
            response.setStatus(response.SC_UNAUTHORIZED);
            response.setHeader("WWW-Authenticate", "NTLM "
                  + new
sun.misc.BASE64Encoder().encodeBuffer(msg1).trim());
            return;
        }
        else if (msg[8] == 3) {
                off = 30;
                length = msg[off+17]*256 + msg[off+16];
                offset = msg[off+19]*256 + msg[off+18];
                s = new String(msg, offset, length);
                //out.println(s + " ");
        }
        else
                return;

        length = msg[off+1]*256 + msg[off];
        offset = msg[off+3]*256 + msg[off+2];
        s = new String(msg, offset, length);
        //out.println(s + " ");
        length = msg[off+9]*256 + msg[off+8];
        offset = msg[off+11]*256 + msg[off+10];
        s = new String(msg, offset, length);
        Pattern pat = Pattern.compile("[a-z,A-Z,0-9]+");
        Matcher mat = pat.matcher(s);
        String s1 = "";
        while(mat.find())
        {
                    System.out.println("Got name: "+mat.group());
                    s1 = s1+mat.group();
        }
        System.out.println("Got name: "+s1);
        if(s.indexOf('.')!=-1)
        {
            System.out.println("dots!!!");
        }
        s.replaceAll("[.]","");
        System.out.println("Got name again: "+s);
        out.println(s);
        out.println("Hello <span style=""
            + " height:10;filter:glow(Color=#009966,Strength=1)">");
        out.println(s + "</SPAN>");
          out.println("<br><br><b>"+s+"</b>");
        }
%></BODY>