Indeed, I can confirm this happened to me multiple times while trying to stay covered in a watch tower. One of the many stance-related bugs that could easily be fatal for obvious reasons!

This happens to me seemingly at random in all vehicles, not just the ATV. The vehicle seems stuck turning for a while then fixes itself.

I really don't believe that having a mod-able game and having a mostly script/cheat-free multiplayer experience are mutually exclusive. cf. Quakeworld, Quake 3.

i5 2500K
8GB
2x 560Ti SLI
win7 64

Same problems as everyone else here; my numbers vary from 35-40fps on a good day to 11-25fps more typically... without mentioning the periodic drops to 0fps for up to 10 seconds. I absolutely love this game so far, it really excites me, but no matter how good the game is, it's simply too frustrating when the FPS drops so low that controlling your movement (aka. playing the game) becomes near-impossible. Like radek, I too find myself gravitating toward bf3, even if it's not the same kind of game and has many shortcomings of its own, simply because the difference in FPS is so important (60-100fps in that game).

All of which is to say that I think this issue deserves absolute top priority and I hope you are able to address it soon, or at least by the release date. Thanks and good luck!