Weird issue using triple monitors

[soulesschild]

I have 2x 4850's. A VisionTek and an Asus. The VT powers my dell 30wfphc, and the asus powers 2x 2007wfps. Now occasionally I get some super crazy color/artifacting distortion on the two 20 inch screens after prolonged usage of my computer. Is this a temperature issue? A restart fixes it just fine.