Need help with the ifly 747 autopiolot

My ifly 747's autopilot suddenly went haywire two days ago. It was working very well a week ago but 2 days ago it went haywire and takes the plane in circles. Tried to fly from KSEA to KLAX. The autopilot works taking the plane to a heading of 146 initially and on its way to FL360. But half way to FL360, it went berserk and takes the plane heading 340 then fly around in circles and then crashed. I tried to press heading hold and take it off from autoheading but it still take the plane in circles. Pressing the true heading other than norm indicated heading is useless also. Anybody has any idea what is happening? :-/