I've put together a new computer that will do double duty as a HTPC. My problem is that when I plug a HDMI cable in to the computer I get a never ending series of beeps that sound like USB devices being plugged in and removed.

The cable is plugged in to my receiver, which is in turn plugged in to a projector. When I bring up the multiple displays page in the nVidia control panel, one of the two displays listed keeps alternating between my Optima HD70 projector and my Yamaha HTR-6090 receiver. The computer can't seem to decide which it needs to talk to, and I don't get any picture on my projector at all while this is going on.

Any solution for this?

Video Card?
OS?
Do you also have a computer monitor connected? What type of connection?
What happens if you don't have the projector plugged in? Are you trying to run it in clone mode or extended desktop?

Video Card?
OS?

The video card is a GeForce GTX 260. OS is Vista 64. I have a Windows 7 partition and it does the exact same thing there.

Do you also have a computer monitor connected?

The computer monitor is hooked up via a dvi connection and works fine.

What happens if you don't have the projector plugged in?

The receiver alone shows up in the control panel app and I can set it up as a second monitor but as soon as I turn the projector back on, it disappears and the projector takes its place, then back and forth every couple of seconds.

Are you trying to run it in clone mode or extended desktop?

Clone

Also, I get the same results on two different HDMI cables.

Just guessing here - but it sounds like a receiver issue and the PC shouldn't be able to see the PJ. I'm assuming you've tried other inputs on the receiver just to see if that changes things-

The clone mode seems off, only as there don't seem to be too many folks that have the same native rez on their monitors and their PJs - but I'm sure you've got it set right, and that would cause issues other than what you're seeing.

Latest NVidia drivers as well-yes?