Help! My Amp turns off randomly!

Hey, I'm a novice in terms of audio's and speaker systems. I just bought a Onkyo HT-S670 home theater system. After setting it up I tested it out by playing "Bourne Supremecy" nd it worked great! But today my Reciever seems to randomly turn off. For some reason whenever I try to play any kind of dvd or play a video game with my surround sound without turning down my sound to around 30, my system turns of into standby after about a minute. The weird part is that if I keep the sound pretty low, it won't turn off, or if I change it to stereo instead of Dolby D or Pro Logic. The stanby red light also starts to blink when it randomly turns off. I tried calling Onkyo but the wait time was wayyy too long and I hung up. I'm hoping one of you could help me solve this problem! Thanks alot!

(P.S. I changed the outlet from which the reciever gets it's power but the problem still occurs. The model number for the reciever is HT-R420)

My first thought was that it was overheating, but i dont think it would overheat that quickly. Perhaps your speakers are too low of an impedance to be driven by that amp. Or you havent got the ohms switch selected to the right setting if that reciever has such a switch.

If you have the amp stuffed in a cabinet somewhere try letting it get good airflow and see what happens, and make sure your amp can handle the speakers impedance. Otherwise there might be something wrong with the amp.

Check if your receiver doesnt have its "Automatic Off" function selected.

This function is designed to turn off the receiver automatically when the TV audio source is selected and your TV is turned off (or not generating any sounds for the receiver to amplify).

It is a very convenient for people that use their receiver and HT speakers as the only audio source (dont use TV speakers), but can cause problems when your TV audio source is not connected to the receiver.

hope this helped. HG