As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF WE LOST VNAV ON THE FMA AND VERTICAL GUIDANCE ON FLIGHT DIRECTOR WITH ERRONEOUS LNAV INFORMATION ON THE FO PFD. CAPTAINS LNAV GUIDANCE NORMAL. GROUNDED - YES. PERFORM B737-800 FIM 34-61 TASK 836 CYCLED BOTH FMC'S CIRCUIT BREAKERS. NO DEFECTS NOTED.