TX-SR875 HDMI audio problem

I have a Dell Studio 1735 laptop w/ BD ROM and an HDMI out jack. It is connected to my 875. When I try to listen to the Itunes or Windows MP11 I get only 2.1 stereo and sub , no center or surround L/R. I had it connected to HDMI input 3 and had "PLII music" as the selected default and used to get wonderful surround 5.1 sound. Now, before I start the music the 875 display shows "PLII Music", but as soon as I hit play the display changes to THX Movie. And I get 2.1 stereo only. I can select "all stereo" and get the surrounds to play L/R stereo, but no center channel. The center and rear speakers work when I use my Cable box or Bluray player via HDMI and even though the 875 automatically selects the correct surround mode for the given input, I can select other listening modes just fine. When I test (configure) the computer sound processor (it's a laptop so no card) via the HDMI connection I can click on each connected speaker icon and get sound through the 875 to ALL 5 speakers. I have swapped the HDMI cable out. I have tried another HDMI input. I have downloaded the latest updates for computer including the IDT HDMI driver. Since I can get the 5.1 sound in the IDT HDMI test mode, I can't understand why the 875 switches to THX and only plays 2.1 stereo. I have used the 875 menu to preset the audio mode for HDMI to every surround configuration and still get 2.1 sound. Any ideas? Since it used to work I'm guessing something in the 875 HDMI circuitry has died?

In regards to your issue- it would possibly be more effective to contact our Product Support Dept for further assistance with this specific issue via our phone number and hours of operation below. We would like to speak with you and work to troubleshoot and resolve your issue, with you having access to your unit, as prompt as possible. Please contact our Product Support Dept for further assistance with this specific issue via our phone number and hours of operation (Monday- Sunday 24 hours a day: (800) 229-1687; option #3 PRODUCT SUPPORT). We would like to speak with you and work to troubleshoot and resolve your issue as prompt as possible.

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