As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE IN STRAIGHT AND LEVEL FLIGHT F/O PR GOT VTK AND DUAL FMC FAIL, DROPPED OUT OF LNAV/VNAV AFTER ABOLUT 45 SECONDS BOTH FMC RETURNED BUT ALL DATA WAS BLANK. GROUNDED - YES. FMC BITE SHOWS FMC-L RESYNC MSG ON PREVIOUS FLT LEG. ACCOMPLISHED B737-800 FIM 34-61 TASK 832 VERIFIED OP PROGRAM & ALL SOFTWARE SAME.