ghosting monitor?

Hi All, I have a macpro 4.1 2 x 2.26 quadcores) with 32gb of ram. I am running a dell 30 in monitor 2556x1600 and a 20 in monitor 1600x1200. At first I ran just the 30 inchand all was fine. Now with 2 monitors after a while about 1/2 hours the monitors act wierd. I get ghosts of windows and images: any ideas?

Which video card are you running in the Pro? Have you checked it to see if it's overheating? It almost looks the card is getting hot - unless you're running two video cards, one for each monitor?

there are 2 video cards each with 512mb. I am only running photoshop so I don't think there is a high demand on video cards running one monitor each.