The problem I experience is happening when pressing the middle mouse button (or equivalently "mouse wheel button") in a game where you can aim with the cursor.
I am using a "Mad Catz R.A.T 3"-mouse but this may not be the problem because I experienced the same problem with a mouse from Microsoft.
The problem is that the cursor jumps to some "random" (x,y)-coordinate after pressing the middle mouse button. For me this is happening for the games CS:GO and Darksiders II.
Note that this problem is neither happening at my desktop nor in many other games (but I did not test other similar games though). My middle mouse button has the standard configuration, i.e. it is configured to trigger "Autoscroll", if available (usually in desktop only) and by pressing it on a tab in a browser, it will close the tab.
The following YouTube clip describes my problem pretty well (except that the video owner experiences it with the "right mouse button"): http://www.youtube.com/watch?v=lHd8yxCZqrM
Now this could also be Steam related (because both games are running through Steam) but I can't figure it out.