As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 390, A TAKEOFF CONFIGURATION WARNING LIGHT AND WARNING HORN ILLUMINATED AND SOUNDED. NO OTHER ABNORMAL SYSTEM INDICATIONS. PRESSURIZING NORMALLY. LIGHT AND WARNING HORN CONTINUOUSLY ON EVEN AT IDLE POWER SETTING. LIGHT AND HORN STOPPED WHILE DESCENDING THROUGH FL 205. R & R THE SWITCH IAW MM.