I have come across a few people with the same issue that seemed to have solved the problem with System.addProperty(\"webdriver.chrome.driver\", \".../chromedriver.exe\");<
Since you're using C#, you should use the constructor overload for ChromeDriver that allows you to specify the path to the directory containing chromedriver.exe. To wit:
IWebDriver driver = new ChromeDriver(@"C:\my\path\to\chromedriver\directory");