New member with a serious Receiver problem!!

[Blame66]

Hi guys, I am new and blu. I recently bought a PS3 60gig, Samsung LCD 40 inch 70s series, have now 26 blu ray movies, 4 in order (love amazon bogos), and have a Sony STRDE-575 receiver. No money to upgrade that now. Here is my problem: I moved my home theatre to another room, hooked up the PS3 throught the optical cable, everything works except my center speaker. I have checked the actual center speaker and it is ok, checked the wire and re stripped the tips of the speaker cable. I turn off the receiver for a couple of hours, turn on the receiver and do a test tone and i get sound from all the speakers. As soon as i play a blu ray movie, i get complete sound from all the speakers for about 2 minutes. Then i get no sound from the center speaker, all of the other speakers sound great. I have been frustrated for the last 4 days, unable to watch movies, even called Sony. Please help!!!