My Harman Kardon AVR430, bought new several years ago, recently started to turn itself off while in use. It doesn't happen with any particular pattern of usage. Last week, it happened after about 2 hours of watching a movie, it felt kinda hot to my hand, but nothing outrageous, nothing more than before. I stopped the movie and called it a night. Then last night, it turned off 5 minutes into a movie, felt room temperature cold to my hand, about 70F. I turned it on, a few seconds later, it shut itself off. I turned it on again, and it stayed on, finished the movie. Any ideas?