What I found many pilots did not know was that leaving the cruise winds in for lower altitudes affected the descent profile calculations. For example if you had in winds for 310/350 at a waypoint near departure, and were now at 390, it would still factor in the 310/350 winds for the descent. If they were not valid, as soon as the aircraft started to descend, the profile would change. Deleting cruise winds after climb to the next level and all but the final level before descent solved the problem for me.