I doubt it's the problem in this case, because you mention the same effect appears on the LCD in Live View...
Do you regularly format the memory cards in the camera (and not in your computer)? If you haven't formatted recently, you might try that.
Another thing that probably doesn't apply in this case is how you download the images. Most of the problems I've had over the years (very few, actually) have been due to poor card reader connectivity.
Before you send the camera off, you might try doing a "reboot" to see if that helps.
That means turning off the camera, removing all the batteries (including the silver memory batt), turn the camera on and press the shutter release button once. It won't fire, but this drains any remaining power in the camera and forces it to reboot. Turn it off, put the batteries back in, turn it back on and check the time/date in the menu... You should need to reset it, if you got a proper reboot. You also might need to reset other menu/custom function settings.
You also might check the firmware and update or reinstall it.
Actually I suspect the camera will need to go in for service.... But the above items don't cost anything and are easy to try, before shipping it off.
On the bright side, the camera is still under warranty since it was bought in Sept. last year.