As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AT CRUISE, LEFT MCDU WENT BLANK AND APPEARED TO PERFORM REPEATED REBOOTS / BIT TESTS. AFTER SEVERAL MINUTES IT RETURNED TO NORMAL OPERATION. GROUNDED - YES. PERFORMED FIM TEST 34-61 TASK 836. BOTH FMC'S AND MCDU'S WORK NORMALLY NOTIFIED SEAMC JEFF.NON ASA EMP, FAA #2777833.