black flicker and tv shut-off with new PC

[rosemary]

[Edit: Oops, the thread title was supposed to be "with new video card", not "with new PC"]

Recently my old video card melted and I put in a new one (Sapphire Radeon HD 100252HDMI 4550 512MB DDR3 HDMI / DVI / VGA PCI-Express Graphics Card). Like a bad scientist, I also simultaneously upgraded from no-service pack Vista to Vista SP3.

So now when watching videos in Sage, there's a black flicker every once in a while. It's pretty random and only lasts for about an eyeblink. Then there's the turning off. This is also random. It can happen when you've been watching a video in Sage for an hour or for just a few minutes. May happen a couple of times, or maybe just once per night. Maybe not at all on a given night. What happens is that my TV (pioneer 4280HD plasma), will spontaneously shut off. Now, it's not the normal type of standby shutoff when I hit the power button on the remote. When I do that, the blue power indicator turns to red and pressing the power turns it back on rather quickly. Instead, when this happens, it changes from a solid blue light to a slow blinking blue light. When you hit the power on the remote, it takes much longer than usual to come on and says something like "starting up." It's almost like one is standby and one is full shutdown (though I would think there would be NO light and not a blinking blue one).

Now, while the TV is off, the computer is still humming along, playing whatever video you were playing. It doesn't shut down or go into standby or anything. I can even VNC it from another computer and still be working on it. But my guess is that somehow it's deciding to tell the TV to turn off when it shouldn't.

So, does this ring a bell with anyone? I strongly suspect that it's more related to changing the video card rather than the Vista service pack, but it's a close call. I'm open to suggestions.