I've got a Westinghouse 32inch flat screen HDTV and a Phillips sound system with DVD player...Everything has worked fine till the other day I put in a rented DVD and the screen goes blank and says invalid format...this has never happened before...even one of the DVD's that played in it before has the invalid format error...some dvd's play and some dont...I seems that maybe one of the setting have been changed but I'm not sure...anybody out there know what might cause this error and how to correct it?????