So, I just installed New Vegas on my new PC, and right after the intro I notice that the movement feels like I'm walking on ice or some other slippery surface. After I've stopped pressing W my character slides a couple of feet forward. It doesn't happen every time I let go of W, but it does it most of the time. I'm pretty sure this never happened on my laptop that I used to play on. Is this a known issue or am I on my own?

What other input devices are connected? These Bethesda PC games work poorly with both keyboard and controller or just a joystick, move around on their own, different odd symptoms.

Nothing but KB+M.

Wired or wireless? If wireless, hunt up old wired units and try those to see if there are spurious signals coming in along with the actual signals you send.

Nope, not wireless.