Hi jacknick, it's always a good idea to perform a factory reset with open box. This will ensures that all settings are back to their original factory defaults.
Using the buttons on the receiver:
1 - Turn off the power using "ON/STANDBY" button
2 - Press "ON/STANDBY" button while simultaneously pressing "Surround Mode <" and "Surround Mode >" buttons
3 - Once the display starts flashing at intervals of about 1 second, release the two buttons.