Using the Beo4, turn the Avant on and then press "menu" "menur" to see the set up menu. Go to #7 and press go for external sources and look at the SAT listing.
Change the SAT listing to none, exit the menus and power down the AVANT for 15 minutes.
Bring the Avant back up, go back to external sources, and change the SAT listing to the selection that you want.
This has happened on my unit, but usually because someone has accidently fiddled with the set. (usually me)