Windows 7: hdmi and surround sound

I have alot of trouble with getting surround to work through hdmi. My setup is the following - the Revo 3600 is connected through hdmi to my Denon AV-Receiver which sends the sound/picture to my Sony TV also through hdmi. But I have alot of trougle to get surround to work. When I look in the control panel and sound I see the Digital sound (hdmi) and this is set as default, but I can only select 2 speakers and is states that HDCP is not supported? How do I get this to work?

I have the exact same issue. The issue came out of the blue after I had done a reinstall.

HDCP has someting to do with the vid card. The newer cards all have this.
On mine there is a jumper wire that connects vid card to the mobos onboard spdif. From there you would connect a spdif cable from mobo panel to the reciever.
I think you will have to connect headphone jack/or sound jack from puter directly to sound jack in TV input. From there use the TV's sound output and connect to receiver, using TV speakers and stereo speakers. Just because you have an HDMI out, does not necessarially mean its sending sound signal. I connect my computer from vid card to TV. Thats DVI to HDMI. No sound signal thru HDMI. I use a 2 channel phone jack from mobo to HDMI inputs, sound input. Only a stereo signal! Sounds great when I add stereo and TV speakers.

Well I solved it by installing new audio and graphics drivers from nvidia then I was able to set my system to 5.1 speakers. However it messed my movied up, so now I cant play movies from WMC - it crashes after 10 seconds. And some times when I try to play a mp3 from WMC I get som strange error and have to restart WMC before I can play any sound again.

I have a ATI Radeon 4550 HD graphics card with HDMI out. It does support sound, it definitely used to output in 5.1 surround just fine. I'm currently running Windows 7 and last night I installed the latest Realtek drivers, then the Realtek HDMI drivers. I now have the option when I select my playback device for 5.1 surround but when I do the test.. my receiver still only shows a signal to output in stereo at 48hz. I then installed ffdshow, and well.. nothing still. It's getting quite frustrating.

I have the exact same graphics card and issue.. I uninstalled Windows 7 and reinstalled Windows Vista.. and my issue is still there. Did you ever get it solved? If not, can anyone else here shed some light? This is driving me nuts!