[Wayne 962]

It could be the shifter mechanism, but it also could be related to the traction control system on your car. I have a 1998 E39, and it has built-in traction control when the wheels spin on wet surfaces. This doesn't happen a lot, so I don't really have very much experience with it, but one or more of your wheel sensors may be faulty, resulting in problems with the car deciphering the road conditions. This is just a best guess...

- Wayne