When I move my character and stop, he either stops on the spot or continues for half a second. It's completely intermittent and random which is driving me absolutely crazy. I would accept either system, but not both. What to do?

Probably this is some kind of lag, and the "randomness" is actually when the game demands the most processing/memory/graphics power... So try lowering your settings.

No, no, that's not it at all. It's hard to explain, but some games, when you let go of the movement key, the character stops on the spot, like immediately, and some games keeps the character moving for a few tenths of a second and gradually come to a stop, like you stop on ice. My New Vegas has both, sometimes the character stops immediately and sometimes like on ice.

This is ruining my game, I can't play it like this.

Well, lowering your settings is still good advice. A lot of glitches are due to trying to run the game higher than your machine can do so.

Even if it is as you say, the best advice we can give you is lower your detail settings, don't run other programs at the same time, and defragment your hard drive. You know, standard PC maintenance. If you aren't on PC, I don't have any advice for you.

-Nukeknockout