AppleTV interrupting while playing movie

My new black Apple TV (3rd generation) is plugged into my flatscreen by HDMI. All worked fine.

A few days ago there were sudden "interruptions" while watching a show from netflix: no video, no sound, black screen. After a few seconds, video and sound returned, my screen shows a message that it is connected to a HDMI source.

From that message, I understand that the HDMI connection was lost. ATV has the latest software, the interruptions come and go, no pattern to be detected.

Anybody know what I can do, apart from returning the ATV and getting a new one?