Omnifarious

I am trying to set up my computer to play video through my Samsung HLT5057SX/XAA. I have a Radeon HD 2400 Pro graphics card. I am outputting the video through the DVI output on the HD 2400 by using a DVI to HDMI converter doo-hicky and then running the HDMI cable to the TV. The HDMI cable plugs into the "HDMI3/DVI IN" input. The video works fine, but where I'm having trouble getting the audio to work properly. I am running the audio out of the speaker jack in the computer through a mini-jack to RCA Y-splitter cable. This cable is plugged into the "DVI IN" input on the TV. Here's where the trouble comes. I have a pioneer receiver that controls my surround sound system. I use an optical cable to connect the receiver to the TV. The cable runs from the "DIGITAL AUDIO OUT" output from the TV to the input on the receiver. When I watch a video from the computer, I get audio through the TV's speakers, but not through the surround sound speakers. The frustrating thing about this is that the exact same setup works just fine from both the Component inputs, as well as the "PC IN" input.

If anyone has any suggestions as to how I can get the audio from my computer out through my surround sound system, it would be greatly appreciated. Thanks in advance!