blocky segment on my LCD... why?

I have recently noticed a portion of my screen gets blocky artifacts when there is any motion in that area. It's a square area about 200x200 pixels. Here's a screenshot I was able to capture:

In the picture it's just gray, but when there is any motion, say scrolling in a web browser, it will get blocky and skip around.

I first noticed it when watching TV full screen immediately after installing my Formac Studio TVR. I thought it was just a buggy application, but now I get the same problems everywhere else.

So does anyone have any idea what causes this? I don't see how it could be software-related since it happens everywhere... maybe it's a graphics card issue?

Any help would be greatly appreciated!

 

Just reconnected the cable firmly... didn't help anything

any other ideas?

 

I guess while I'm at it, here's another thing that's been bugging me...

This one has been happening for a long time... I keep hoping that 10.4.3 will fix it, but has anyone else had problems with their CMD-Tab menu too?