My first thought is: Is the main powered up enough? I can "steer" the boat by playing the traveler with a fairly tight main sheet.

My second thought: Make sure the rudders are not getting "caught" and are fully down (but this would also cause helm issues upwind).

The first weekend I had my boat I was having a lot of weather helm, Matt simply retied the knots that end up in the rudders so that they did not interfere with getting the rudder all the way down. I felt like such a ^%^$#& neophyte (which I am). It just goes to show that if somehting is that BAD compared to last time, it is something outside the setup.