title: SPContext.Current.Web.CurrentUser returns misleading value
body: <p>I'm trying to find out current user name for my sharepoint application. There are more that one way how to do this. However the sharepoint way returns misleading value. </p>
  
  <pre><code>System.Security.Principal.WindowsIdentity.GetCurrent().Name // returns MY_COMPUTER\\my_user
  
  HttpContext.Current.User.Identity.Name // returns MY_COMPUTER\\my_user
  
  HttpContext.Current.Request.ServerVariables["AUTH_USER"] // returns MY_COMPUTER\\my_user
  
  Microsoft.SharePoint.SPContext.Current.Web.CurrentUser.LoginName // returns SHAREPOINT\\system
  </code></pre>
  
  <p>What is the cause of this behavior? Will I encounter problems if I'll use non-sharepoint way?</p>