I hat this happen twice today. I was first running but after having walked for a while my character was also stuck in walk mode. If i wanted to run i hat to press and hold shift. Both times i got rid of it by reloading the latest savegame.
I'm on xbox and I have a similar problem. During melee fights, when I charge at an enemy my character will continue to spin in a random direction after dealing the first blow. I've changed controllers and tried a few other things, but the problem is still there.
I had this problem on PC several times. I figured out that if you alt-tab out of the game, hit caps lock, then tab back in and hit caps lock again it will clear it up.