Back in April we had the GPS issue that caused the magnetic heading to be displayed incorrectly and cause windspeed and direction to be wrong. I installed the Beta software to correct the issue and flew the aircraft almost 20 hours with the issue resolved. I then installed the latest release last week and flew a cross country flight from Tucson to Albuquerque. For the first hour of the flight Heading and windspeed were correct. Then about an hour or so into the flight as I began my decent into Albuquerque the heading was 10 degrees off roughly which caused windspeed and direction along with the synthetic vision to be way off again. Any ideas?