So twice in the past half hour or so my character has found himself unable to stop moving in whatever direction I was headed in at the time.

It takes nothing less than to completely restart the game to get it to stop. Quickloading my previous save doesn't do it, nor does quitting to Main Menu and going from there.

Obviously this is a major hindrance. Am I the only one encountering it?

EDIT: Just to clarify. auto-walk is not on.

Stop dripping cheese doodles into the keyboard....

do you have any kind of joystick or anolog pad connected to your PC?

I had this problem in Oblivion, then I noticed my wireless keyboard was blocked/low charge. Wired or wireless?

try pushing down really hard on the w button, I have had this happen to me in other games and that usually fixes it