Artifacting on desktop

[TheKeir]

I bought this PC a little over 2 years ago from PCS. In the past week, I've been regularly getting some artifacting (or whatever it is) on the screen when I'm in certain applications. It appears and disappears at various points, depending on where the mouse moves and which window I have open.

Here are two examples I just screenshotted:

http://i60.tinypic.com/2gwxnx0.png
http://i57.tinypic.com/25klq9s.png

Look to the bottom of the screens. The lines are sometimes black, sometimes multicoloured.

Is this a sign of the graphics card failing? It's really annoying me, particularly since it's so jittery and changes a lot. (Though it's always horizontal lines)
If so, can I return the PC or graphics card and get a replacement GPU?

I bought Silver warranty, and the card is a Powercolor 6850.

If it's a fixable problem, any advice would be welcome thanks!

 

[Rakk]

If so, can I return the PC or graphics card and get a replacement GPU?

I bought Silver warranty, and the card is a Powercolor 6850.

Since you have the silver warranty and it only covers parts for a year then it would not cover a failing/broken GPU after 2 years, noting that I don't know if those problems means it is failing or not, I'd wait for some other replies for the answer to that one.