I am using selenium with python and have downloaded the chromedriver for my windows computer from this site: http://chromedriver.storage.googleapis.com/index.html?path=2.15/
I encountered the same problem as yours. I'm using PyCharm to write programs, and I think the problem lies in environment setup in PyCharm rather than the OS. I solved the problem by going to script configuration and then editing the PATH in environment variables manually. Hope you find this helpful!