As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE:SDR AIR TURN BACK. BOTH FMC'S FROZE UP AND SHOWED STANDBY ONE IN SCRATCH PAD. UNABLE TO CLEAR SCRATCH PAD & ENTIRE ROUTE CLEARED OUT INCLUDING PERFORMANCE PAGE. REPLACED LT FMC PRECAUTIONARY PER AMC. R&R'D LT FMC IAW AMM 34-61-01-2. OPS CHECK GOOD.