I am having a similar problem with my 40gb PS3. I use my PS3 in my theatre room and it is hooked up to an amp and digital projector. The PS3 has worked flawlessly for months then last night mid way through a DVD the audio and video cut out and come back straight away, this flickering occurs every 3 secs. It is definitely the playstation as I have ruled out an problems with the amp and projector by hooking up different hardware to them all. It is not related to the DVD I was playing as I have tried numerous DVD, Games and also while the PS3 is empty and just on the main menu screen
Its also not a distruption to the power supply other wise the playstation would keep going back to the main menu screen rather then continuing the movie or game with continuous breaks in the video and audio.
Can anyone help???