Problems with optical audio output

I already posted this in the Reciever forum, but not really getting any help there, so here it goes....


I'm hoping someone here can please help me out, i'm desperate and frustrated, i've been dealing with this issue for almost 2weeks now and is quite annoying.


Let me start by telling you my setup:


Comcast HD/DVR Dual Tuner (Motorola DCT 6412) - connected to tv via component video and analog rca cables, also connected to my reciever using optical cable to input 1 of reciever


Sony 51" KP51W5520 Rear Projection TV


Sony DVPNS995 DVD Player - connected to tv via HDMI cable and rca audio cables, audio is also connected to reciever via optical cable to input 2 of reciever


Harmon/Kardon AVR635 Reciever


My PROBLEM is that on non-digital channels, i get no audio from my STB to my Reciever. I do get audio from digital and HD channels through the optical output of my STB to my reciever, but when you turn the channel to analog, i get nothing, except for audio to my t.v. via the analog rca cables. At first, i thought my problem was my reciever, but after hooking up my STB from a different room (Motorola DCT 6208 HD/DVR Single Tuner), the audio output to my reciever via the optical cable works on all channgels, digital or analog just fine. So, this tells me the problem lies with my STB. Now, here is where it gets interesing...if you unplug the power from the DCT 6412, let it sit for a minute, then power it back on and tune to a analog station, it WILL play audio via the optical cable to my reciever for about ONE minute, then i can hear the STB's Hard drive make some noise like it is working, then the audio stops and does not continue at all, unless i change the channel back to a digital channel, then audio works fine. I've already had Comcast replace the DCT 6412 once already,and i'm having the exact same problem. So What is the problem? Can someone PLEASE help me!