Firefox webdriver opens first run page all the time
How to disable this "first run" page once and for all for FF?
When FF driver is created, it opens tab with - https://www.mozilla.org/en-US/firefox/42.0/firstrun/learnmore/ and additional tab with target page.
Answer
To turn off this annoying start page:
in C# with Selenium 2.48 I found the following solution:
FirefoxProfile prof = new FirefoxProfile();
prof.SetPreference("browser.startup.homepage_override.mstone", "ignore");
prof.SetPreference("startup.homepage_welcome_url.additional", "about:blank");
Driver = new FirefoxDriver(prof);
...and it will never bother you again.
Note: One of these settings alone will also work. I use them together to make it bullet-proof.