Problem with a Mac Mini and VT2430 LCD TV

[PeterB]

I'm trying to use the TV as a monitor. Running 10.8.4 on the Mini, connected the VT2430 using HDMI, set for NOT mirroring, and using the monitor's 60hz refresh rate setting in the Displays preferences. The output on the VT2430 looks grainy and poor. Any ideas how to fix? (Unfortunately, this TV only has HDMI and VGA in, no DVI in...)

TiA