I've got the same issue with my GATEWAY XHD3000. Black on the left side, dark in the middle, and clears up on the right. To me this appears a simple fix of the backlight, but i've not taken mine apart yet to look at it. I was supposed to be covered under a 2 year circuit city warrenty, but when I tried to call the now bankroupt company, they told me they honor their warrenties, but could not find any part of the company that will work on the over 27" monitors, hence, NOTHING YET! And I paid them and extra $200.00 dollars for this piece of S#@%!
I hope someone finds a service manual, and we can at least order a repair part. I'll keep looking on line, since so many of us are having this issue, someone one somewhere must have a solution!