Hud issue when watching a movie

Hello all
first of all, really sorry for my english, i am french..

i have some problem when i am watching a movie.
the “hud” (movie picture, infos, play/pause button etc…) appear by itself during the movie. (so i dont touch anything, and hop, it appear)

so i have to remove it with my tv remote manually.
then it comes back again, and again, sometimes every minuts.

so i can not watch movies, and can not read subtitles..

my system:

-RPI 3 + heat dissipator.
-5V 3A power supply special for raspberry 3
-plugged on my RPI 3: only HDMI and RJ45, nothing more (sometimes a game controller)

-RECALBOX last version
-the movies are on my old RPI B NAS, everything communicate with samba (i have some win7 computers..)
and everything is connected with RJ45 on 1Gbps switch, and the video is smooth. no stuttering or lag issues

any idea where does this come from ?

thanks !