During set-up of my surround sound, I notice that my H/K AVR-430 receiver keeps shutting down for no reason. The receiver is plenty powerful enough to run the NHT Super1's and Super0's (6 total). What could it be? It's grounded to a surge protector/outlet. Could it be a bad fuse? Defective receiver? It works for 10 minutes sometimes, then shuts off as soon as I start it up. Any ideas????