A name was started with an invalid character. Error processing resource 'http://192.168.1.4:8081/Default.aspx'. Line 1, Po... <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" -^
You need to look for a forum dedicated to installing/configuring ASP.NET on IIS, look under
http://forums.asp.net/ . This forum is not about ASP.NET or IIS, it is about the XML APIs in the .NET framework.
The error sounds as if the server is not processing your .aspx file but rather sending the source of it to the client. That sounds as if ASP.NET is not installed/configured properly for your web server.