The flash is the picture changing to different resoutions...depending on the television that will happen if the scenes and game play are in different resloutions...most HDTVs dont have this issue but some current and many older HD sets do this because they don't have the ability to change resloutions on the fly...I had a similar problem with my PS2 when GT4 came out I havent looked in the menu array on my PS3 but there should be a setting to put the unit into a fixed resloution instead of dynamic just go in there and set it to 770p or whatever you want it to be set at that way the picture will not flip