2002 v40 had the same problem.... described as the trans going into a "false neutral" between 2nd and 3rd. Would happen a coupleof times a week. It would momentarily feel like it really went into 'N' when I hit the gas and would rev up to 3,000 or so and then almost immediately fall back into gear. Took it to volvo who replaced the TCM (under warranty). This was 3 years ago and it's not happened since.