My 26" Display No Longer works

On my MBP Retina (10.8.2)

My INSIGNIA 26" display in one office no longer works, while the Samsung 32" display in my other office works perfectly.

Not sure what this is happening now as the Insignia display had work fine until recently.

I have changed to a different HDMI cable and still nothing.

When I click on to the black/blank display, sometimes small portions of the screen appear.

I can also see my mouse arrow on the black/blank screen, which indicates some connection is being made, but not all.

Any help would be appreciated.