Sounds strange. Are you certain you have connected the digital IN and OUTs correctly. The Digital cable does not go to the LINE IN, but to the DIGITAL IN connection. And you must connect the daisy-chain properly to the next speaker.
Also, make certain you have the right Option setting - though I don't think having it incorrect should cause a problem such as what you are describing.
You can also try the speakers just with the Powerlink cable, to see if the problems persist.