HDMI-DVI cable no longer working, for no apparent reason.

Since installing a Q6600, my DVI to HDMI cable no longer displays a picture on the Panasonic HDTV I connect it to (TX-32LMD70). VGA to VGA (with a DVI adapter) works fine, but I don't have a VGA cable long enough to use, I just used a short one to test and I'd rather not buy a new cable. I've tried with two different DVI-HDMI cables and it's the same.

I've extended my desktop and I can feel the space, I can drag things over, etc, but there's just no picture on my TV. I've tried both HDMI1 and HDMI2 channels on the TV. I've also installed the latest CCC in case it was a driver error or something. My video card is a HD4850 1GB and I'm using XP.

I can't understand why it isn't working - I've used this cable for a good year now and it's been fine. Why would installing a new CPU make it suddenly not work?

Cheers for any help

refresh rates? try setting a low res and altering refresh too if possible. sounds like the tell is getting a signal it can't display.

Tried various resolutions and 50hz refresh rate instead of 60 and it's the same. What's weird is that it doesn't even display the POST on startup either. Nothing at all. It's like it's not plugged in, even though the computer can detect it.