Sapphire Radeon 4850 HD problems

Back in October, I bought some new computer parts in preparation of Warhammer Online. In particular, I upgraded my video card to a Sapphire Radeon 4850 HD. I didn't have any problems at all until a few weeks ago, when I suddenly got some groups of pixels appearing near the top of my screen. They're arranged in groups of squares, forming something like a checkerboard pattern. At first I thought it was my monitor, since I have an LCD, and tried running some various programs to fix stuck pixels. Nothing worked.

Eventually, I entertained the notion that the problem might not be the monitor so I hooked it up to another computer; sure enough, the monitor worked fine. I switched the video card, though, and the second computer inherited the same problems mine was experiencing. The card doesn't show any signs of damage, the fan is working and it's running cool to the touch.

The problem has worsened over the past few weeks, with the pixels growing in number down my monitor (Right now they're about half-way down). It's made playing games a hassle, especially games like TF2 where I don't know if that red spot is a sniper dot or a pixel problem. Forums are difficult to read because as I scroll, the pixels drag behind and make a mess of the page. If I downsize the window then return to it, or switch tabs via Firefox, then the dragged "shadows" go away but will come right back once I start scrolling. My mouse constantly has three lines of miscolored pixels behind it, which is an eyesore.

I've tried purging my drivers via Driver Sweeper, in case it was a driver issue, but after deleting all the drivers and reinstalling the problem persists (And is still getting worse). I've run various malware checks and haven't found anything. I also made sure I used Catalyst Control Center to return all settings to the factory default, in case I accidentally changed some setting which caused the problem. The only thing I can think of at this point is to just buy a new video card, but I thought I would post here in search of advice in case I can avoid spending another 200 dollars.

I'm running Windows XP, Intel dual core 1.8ghz (Overclocked to 2.6) and a little over 2gb of memory (Four 512mb sticks).

 

Why not just RMA the card back to where you bought it?

 

I bought it from Newegg, whose policy (As I understand it) is that all original packaging must be returned along with the product. My dad tore up the original box the card came in, in order to write something on it.

 

:confused Whaaa? Is something wrong with a pad of paper? LOL

Can you try the video card in another PC? Do you have access to a different card you can temporarily try in your PC? Since the CPU is overclocked, one of the first things I'd do is restore it to default settings to see if that helps.