Chome opens a new window on top of the existing window when I run Visual Studio

Chome opens a new window on top of the existing window when I run Visual
Studio

When I run my web application in Visual Studio 2012 it opens the website
as I would expect in the most recently active window of Chrome that is
open. This is all fine and how it has worked for as long as I have been
using Chrome as my default browser for debugging in Visual Studio (all
versions).
However, it has recently started also opening another completely new
window of Chrome with a blank tab over the top of the existing Chrome
window as well. I now close this blank window and find my running website
in the Chrome window behind it.
I am not sure if this was as a result of an update to Chrome (I think so)
or Visual Studio (less likely).
Has anyone else seen this behaviour? More importantly does any know how to
solve it as it is becoming very annoying?