Problem drawing Fronts w/ASUS

[wxwatcher]

I've been using the ASUS messages sent on NOAAPORT (CODSUS not the high res version). On many of the maps the fronts will plot but suddenly DA will draw a vector right off the map. Other examples produce fronts that zigzag but the source data looks good when I look at it visually and plot it by hand. Any ideas what might be causing this?