Suppose you have ASP.NET (or ASP.NET MVC) site.
You want to use Session.SessionID value somewhere (say as shopping cart id), which normally should be SAME value for each request from the same browser (sure unless session expire or user clean cookies, or you forget to store session in some distributed storage and use Web Farm with multiple front-end servers, or you forget to … actually many things might be here).
However you may see every time DIFFERENT value for Session.SessionID for anonymous user!
How? Reason: new SessionID is generated by ASP.NET, UNLESS YOU STORE SOMETHING IN THE SESSION!
For example do something like this: Session["Something"] = 1 after first user request and you will see that SessionID remains unchanged.
Sounds crazy, right???

Few useful ways to get current application domain directory path in .NET
(some for Winforms, some for ASP.NET, some for both):

• System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase)
• AppDomain.CurrentDomain.BaseDirectory
• Directory.GetCurrentDirectory()
• Environment.CurrentDirectory
• this.GetType().Assembly.Location
• Application.StartupPath
• HttpContext.Current.Server.MapPath(@”~\”);
• Application.ExecutablePath
• HttpContext.Current.Request.PhysicalApplicationPath

In Windows 7, Go to Control Panel \ All Control Panel Items \ Programs and Features

Press “Turn Windows features on or off” and make sure that you select following features:

• Under Internet Information Services make sure that you select available options (including options in sub nodes), that you going to use. Usually it is everything, except probably ASP (but make sure you select ASP.NET instead), CGI (if you going to use any CGI development, PHP for example, you need to select this feature), Server-Side Includes, FTP Server (if you not need to setup own FTP Server) etc:

• Make sure you select Windows Communication Foundation HTTP Activation and Non-HTTP Activation features (features used for example for Azure or WCF development) – see illustration above