Hi Folks -

New to Super User, so I hope this question fits in with the guidelines.

Very strange problem I am having, and I am at a loss as to how to continue troubleshooting this one. The basic problem is that when I attempt to watch streamed video on a particular display device (an Optoma HD180 projector), my network connectivity drops like a stone to barely measurable levels.

This is my setup:

I have a Dell H2C 730x running Windows 7 64bit. This particular computer has two ATI Radeon HD 4800 video cards. I have two Samsung 22" monitors connected to one card, and an Optoma HD180 digital projector connected to the other card via an HDMI cable.

My internet connection is normally a reliable 6Mbps.

The problem I am having occurs when I stream video (or even just browse the web) on the Optoma Projector. When I do this, my internet connection drops to practically zero (just a few kilobits per second). When I move the browser away from the projector, and over to one of my Samsung monitors, the internet connection comes right back. Note that the Optoma projector is on and enabled as a third monitor all this time. I can move the mouse around on the projector without triggering the problem.

I tried pinging my router when I was playing a movie on one of the monitors, and I get a 1 millisecond response. However, when I have the movie playing on the Optoma projecter, pinging the router gives me response times in the hundreds of milliseconds, or times out completely. So, it clearly is something local to my machine - and not some sort of throttling occurring down the line.

I would think that it is possibly something to do with the HDMI driver conflicting somehow with my network driver (which is a USB-based wireless connection).

This one has me really stumped. Anyone have any ideas?

EDIT: I am now leaning towards the possibility that the HDMI cable is somehow interfering with the wireless network, when large amounts of data are being pushed through the cable. Is this possible?