As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT NOT GROUNDED: IN CRZ AT FL 390 DUAL FMC FAILURE. LNAV RECOVERED IN 5 MINUTES VNAV REMAINED INOP. QRH CALLED FOR SELECTION OF ALTERNATE NAV SELECTOR, THIS DID NOT CLEAR PROBLEM. ACCOMPLISHED FMC BITE IAW FIM 34-61-00 ALL CKD NORMAL.