Horizontal lines on 42" LG LCD@60hz w/ATI3450HD

Anybody know why i get these horizontal lines on my LCD display?
Heres a couple photos. This happens whenever there is rapid vertical movements across the screen. in 3d games i notice it most, but i was able to capture some photos of it while using Itunes Visualizations.

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Im outputting from the ATI 3450HD using dvi to HDMI and at the back of the LCD it's going into the HDMI port that is also labelled (DVI). The display is an LG 42" 16:9 widescreen Model:42LC2D.

I'm running 1360x768 32bit resolution @ 60hz (anything higher isnt supported by the LG display, even at lower resolutions like 800x600 although the Catalyst Control Center says it can support 75hz). I'm using Cat Drivers Latest 8.11 released this month.

any advice from the pros?

TIA

-J