Just got your reply. Okay, I did call technical support and they suggested just as you did David, to turn the source knob, and it successfully changed sources. The tech support agent then told me to push the "amp" button on the Denon remote until it displayed "call 1 2 3", which it did, and now it switches inputs via the remote and I have video on DVD (haven't tried TV or my other DVD input because my mom had enough of walking up and down the stairs). The weird thing is that I have never had to have the remote on that setting in order for it to work properly. When I told the tech-support guy this he said that that's abnormal. But anyway it's up and running but I won't know about any of the settings until I can check things out.
Thanks for all your help, hopefully everything is okay.
