The AVR won't create a problem with crawling blacks (or macroblocks, or "crunchy blacks") that's a drawback of DVD's awful resolution and encoding.
If the problem only appeared when you changed connections (say from component to HMDI) then I'd say to check to make sure the "superblack" or whatever the manufacturer calls it was set... to cover for it, most manufacturers will crush the blacks... so that everything, say... under 15 IRE will appear as a solid black. Gets rid of that distracting crawling.
But since you kept the same connection, just routed it through the AVR, at first blush it would appear the AVR corrects its own output to NTSC legal blacks. Someone else with experience with that model may be more help, though.
Bren R.
