Selenium UnreachableBrowserException - “Could not start a new session”

Some time selenium unable to reached the browser and through some exception : "Could not start a new session. Possible causes are invalid address of the remote server or browser start-up failure."
Build info: version: '2.45.0', revision: '5017cb8', time: '2015-02-26 23:59:50'
System info: host: 'SmithPC', ip: '10.0.2.15', os.name: 'Windows 7', os.arch: 'x86', os.version: '6.1', java.version: '1.8.0_45'
Driver info: driver.version: ChromeDriver
    at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:593)
    at org.openqa.selenium.remote.RemoteWebDriver.startSession(RemoteWebDriver.java:240)
    at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:126)
    at org.openqa.selenium.remote.RemoteWebDriver.<init>(RemoteWebDriver.java:139)
    at org.openqa.selenium.chrome.ChromeDriver.<init>(ChromeDriver.java:171)
    at org.openqa.selenium.chrome.ChromeDriver.<init>(ChromeDriver.java:160)
    at org.openqa.selenium.chrome.ChromeDriver.<init>(ChromeDriver.java:117)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

To resolve this you have to do only small changes in the host file.

Host file Location : C:\Windows\System32\drivers\etc

In your host file you have to add localhost entry, as i mention below then run your Selenium or Testng code and check it will work fine.

127.0.0.1            Localhost


I am encounter the same problem, after a long search will found this solution and it worked for me, I hope it will work for you also.