Graphics Card malfunctioning

I use my computer monitor for both my Xbox 360 and my desktop PC, unplugging the PC's VGA cable when I need to connect the Xbox. This has been working flawlessly for several months until yesterday when I unplugged the Xbox cable and reinserted the PC's cable. All of a sudden the PC's image started shaking, turned orange and was essentially frozen.

I don't believe that this is the problem but that it merely began at that point. After restarting the computer the the image the monitor showed from the PC was off-center beginning with the windows login screen. Once logged in, the image would shake left and right slightly and appeared unfocused, but at least the desktop was being displayed. If I opened a folder or a program, within a few seconds the screen would begin to distort, get all jaggedy and ultimately turn orange or black except for a thin row of pixels at the top which displayed the actual desktop. I would restart the computer but this happened over 15 times, everytime I restarted.

Plugging in the Xbox, the monitor displayed the image perfectly, without any of the above errors, likewise, by laptop outputted perfectly. I'm lead to believe that the monitor is not the problem. I also switched the VGA cable and tried it with all three devices, and again, the problem only occured with the desktop, leading me to believe the cable wasn't the problem.

When I booted into safe mode on the desktop, the image took the entire surface of the screen and worked flawlessly. Within safe-mode I disabled the graphics card drivers, and after restarting into normal mode, everything worked perfectly. I reinstalled the graphics card drivers, tried the newer ones and the older ones, but none seem to work. I've checked the computer for viruses and malware but I didn't find any. I've tried several system restore points, but the problem persists. I opened the tower, and ensured the graphics card was properly powered and connected, the fan runs perfectly fine.

I'm nearing my wit's end. The computer and all its components are only 4 months old. My graphics card is an HD4850, and I'm starting to think its a problem with the card. Any help/advice in diagnosing and solving this problem?

Thanks

Have you tried reseating the card in it's slot? With the power off of course.

Reseating the graphics card didn't change the situation. Any ideas on a diagnosis or a solution?

It is sounding more like a card problem to me. Can you check the temperature of your card with your ATI software and make sure the cooling fans are actually cooling the chip?

The problem I have is that I can't access ATI CCC in safe mode, but I can't access it in normal mode either as the screen freezes up.

How many connectors are on your card and what type?

My graphics card has 3 connectors: DVI, HDMI and VGA. The DVI and HDMI slots are not in use, and have never been. The VGA cable has not been unplugged for the last two months, and was only unplugged after multiple malfunctions.

If your monitor can support it and you have a cable, switch to the DVI port and see what happens.

My monitor doesn't have a DVI port. This whole problem just happened out of the blue, I wasn't doing any graphically intensive activity. So frustrating, thanks for helping so far. Any other ideas?

I am trying to determine if it is just a bad port or the card. What about connecting your HDMI to a TV?