Answers

Check the weepholes and make sure they are not clogged. These holes allow water to drain outside of the window, and are on both sides of the window. If they are clogged then the water will drain wherever it can - inside your walls and house. When the window is closed, you are making it harder for the water to get inside. I suggest taking the tip of a knife and just cleaning them out to see if that helps. 

Is there a leak when it's raining or is it just when the window is open in general? If it's simply when the window is open, then there could be several varying possible reasons as to why the basement leaks, solely when the window remains open. Bad timing, as off putting as that sounds. If it's when the window is open during a rain fall, the window could have lost its seal. Rain could leak in through the wall and then to the basement ceiling. If that's the case, I would recommend a new window seal, or replacing the entire window altogether. If you have further questions or concerns, please feel free to call our office. 403-343-0393. Thank you!