Yesterday when I played Oblivion I had this backward moving stuck. The S button was not stuck, there's nothing wrong with the keyboard, or so it seemed. I had reconnected to different USB ports and restarted my machine. I wonder if it's Steam related? Anyone had this before? Is there anyway to diagnose what went wrong?

Sometimes weird stuff happens if you have a controller plugged in.

The hell... it's fixed after unplugging my XBox controller.