I haven't had this problem but it sounds very similar to an problem another UK owner had (unfortunately I haven't got her email address immediately to hand and she has since sold her VX). It transpired that it was a shaft rotation sensor - where and which one I can't remember (sorry but it may give u a clue where to look) but she said that it was a 'common problem' (!?). I'll try to track down that email address 4 U.

Kirk