Slider, glad to hear that you solved the problem. As was said, when a shutdown happens, especially if 4 ohm speakers are involved, although the tendency is to blame the receiver and/or the speakers, a little piece of wire is often the actual culprit.
As was also said, you should at least try using the 8 ohm setting, despite what the manual suggests. At the 4 ohm setting the maximum voltage available at the rails in the power supply section is reduced and because of Ohm's Law the maximum current and power available are likewise reduced. The 4 ohm setting should only be used as a last resort if the receiver would shut down at the 8 ohm setting.
