As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TWICE DURING FLIGHT LOST FMC LNAV/VNAV DISCONNECTED MOMENTARY VTK BOTH SIDES BEFORE I COULD EXECUTE QRM PROCEDURES FMC WAS BACK. HAD TO RE-INPUT ROUTE AND PARAMETER A/T LIMIT STAYED ON. GROUNDED - YES. COMPLIED WITH FAULT ISOLATION MANUAL 34-61 TASK 836 FMC DOES NOT OPERATE. AFTER RESET NO FAULTS NOTED.