Every time I hit "X" it brings up the Steam menu. Can't play at all.

I have had this issue ever since I got this controller (not the Nvidia one but a different generic one, thought I should mention that) and every time I hit the “X” button on the controller it brings up the Steam Menu making it impossible to actually play anything. I finally broke down and am reaching out for help because I finally bought Skyrim and for some reason I can only play with a controller even though its for PC. That in itself is a whole different issue which is even worse because Ive just been using my mouse and keyboard for games that I want to use the controller and its been okay but now i cant do anything in Skyrim because nearly every action is the “X” button. Anything you guys can do to help i would really appreciate it very much. Ive been looking all over the net for a solution and ca not seem to find anything so please, anyone if you could help thank you in advance.