title: ASP.NET: How to prevent opening same site a few times in parallel?
body: <p>I'm a newbie in ASP and I've encountered worst developer nightmare: I've received fired worker huge ASP.NET project and I must make some changes on it. One of the changes is to prevent opening same site few times on one Active Directory login (different tabs, browsers, etc...)
  As I've noticed that app is using session. Any ideas to use session to prevent multiple instances of the same site?</p>