wii + downloaded gsmes + onkyo 605 = bad?

[buckshot]

i just bought a wii for my wife (she wants wii fit when it comes out). i downloaded sonic the hedgehog for her and golden axe 2 for me. i have the wii running through the onyo 605 to the tv. the home screen for the wii as well as the online menus work fine, even the games that came with the wii work well. but the downloaded games won't work. i hear the sound, but the video only flickers on every now and then, when it does it quickly moves down off the screen again. i'm wondering, is it sme setting on my onkyo? or something else.