As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE FL 390 RCVD "LDG ALT" AND "NO VTK" FLAGS ON CA SIDE, MENU PAGE ON BOTH CUDS WITH NO FMC CUE. RETURNED TO NORMAL INDICATIONS W/IN 10-15 SEC. GROUNDED - YES. NO LDG ALT OR VTK FLAGS PRESENT. PERFORMED FMCS BITE. NO CURRENT FAULTS FOUND. REF FIM 34-61 TASK 801. NO HISTORY 90 DAYS.