During my last two flights flying the QOTS II B747-400 the LNAV or Heading Mode Annunciator on the PFD, depending on which was selected, has come up with a horizontal yellow line through (indicating a malfunction), the shortly after this the autopilot has disconnected. The first time this happened was after about three hours into the flight. Yesterday it occurred after about 10 minutes into flight.
I am thinking of deleting the aircraft .cfg file - would this be a reasonable attempt to cure the problem?