Visual Studio - Unity problems

I use Visual Studio 2013 Express for Desktops as my IDE. I set it in Unity preferences as my IDE instead of monodevelop. - However, when I upgraded to Unity 5, when I double click on any script, it always open new instance of Visual Studio, never Only the script in VS instance I already have opened. - Also, when I double click on any errors or messages in console it yet again opens other instance of Visual Studio and doesn`t even put me to error/message code line. Do you know where the problem could lie? Thanks.