I've had this same issue since the start. With me it is moving backwards and to the right. I use my mouse left handed, so I use for movement the I, K, L, and J keys. My side mouse button is assigned to the CNTRL key using logitech setpoint. This getting stuck moving (usually backwards) has gotten me killed a lot while questing. I can only imagine how bad it must be in PVP or flashpoints.
I just did some experimenting trying to duplicate it out of combat. One thing I noticed is that the keys that get "stuck" are ones where if I push the CTRL button first and then they key nothing happens. If I push CTRL and then my forward button (the I key), I move forward. If I push CTRL and then the back button (the K) nothing happens, i have to use the K before hitting CTRL. Same with the L button which I use to strafe right, and which occasionally gets stuck. If I hit the K key to move back and then hit the Ctrl Button for a count of more than "one-one thousand" I am stuck moving backwards. However hitting the back button again (without CTRL held down) stops it. Not having the CTRL button pushed down and pushing the "stuck" key is how I can get the "autorun" to stop.
I think I'm just going to remap my mouse button to the ATL key instead of the CTRL key. As another problem this is causing me (only because i'm left handed) is that I like to use U with a modifier key for a nice accessible keybind and in the game that is set to taking away the UI screen, so that happens accidentally sometimes to me as well. the only reason I've not just remapped my keys yet is that the mouse keys for me are set in Logitech and if I change the ctrl to alt I'll have to go to my other games and reset every keybinding that uses ctrl.
Edit: I just tried duplicating this problem using the CTRL buttons on the keyboard rather than the mouse button that I have assigned to CTRL. It does not happen when using the CTRL button on the keyboard. I do not know what this means. I'm getting ready to make my mouse button the ALT rather than CTRL but now am a little worried that it won't fix it, that it is something about this particular mouse button.
