Hello,
I think i can help. My 568.2 suffered the same thing.Locking up,crazy noises, etc. My noises only occured while watching DTS sources.Horrible pops,clicks,wierdo stuff had made me check all my tweeters for damage.
My fix. A 50.00 APC ups battery back up from office depot.Never had a problem again. I have owned both the 568.1 and a 861.Neither needed this or behaved this way.My opinion is that the 568.2 is more picky about its power from the outlet.Here in Florida lightning capital of the world we tend to have dips and all out power outs some that only last a second or two.The 568.2 hated those it would always lock up and i would have to reset.I have had the ups in place for about 3-4 months now with no issues what so ever.Even while watching DTS. Hope this helps you to, Ron

Ron