error getting for Selenium webDriver in dotnet

I'm trying to do automation testing using Selenium in C#.

using (IWebDriver driver = new FirefoxDriver())
            {


            }

It is giving me error : Exception thrown: 'System.Net.Sockets.SocketException' in System.dll Additional information: No connection could be made because the target machine actively refused it.

On other machine, above code seems fine.

Any idea, if anyone encountered this issue ?