i've noticed something similar on my 3805 if i'm switching from SACD to regular CD. if i take out a SACD and the reciever is in the EXT mode and then i put in a redbook CD it won't put out any sound. i have to hit the I. Mode (or whatever it's labelled as) button on the remote and then it switches over and plays. i don't know if that's whats going on with your situation, but i suppose it can't hurt to try.

Who's the more foolish, the fool or the fool who follows him?