As above - after SU12 the problem persists. I don't use fsuipc, navigraph data or simbrief import. After entering by hand the flightplan (init a and b pages populated with fob and weights as well), was entering the EOSID procedure in sec-fpl before engine start. I created the sec fpl by hand - by entering the same airport icao in from/to, then dep RWY with no sid, Point-bearing-distance as per EOSID using airport runway as reference point. The last point of eosid is a hold, as soon as i press the hold function to insert a computed hold on the point-bearing-distance fix the MCDU I'm using goes blank and all systems/buttons etc stop working. Sadly will not have much time on hands to fire up the sim and try to replicate the issue...