Sorry to hear you're having this issue.
Service would have to determine if that's an issue that would be fixed under special conditions, and I couldn't give an indication as to why only half the screen would be turning off. If you want, try calling Samsung Parts directly at 800-627-4368 to see if they might have the part you're looking for, or if it's possible for a service technician to obtain one.
I have a 4 year old 67" Samsung DLP which has worked pretty well other than having to replace the color wheel twice. Over the past 6 months it's developed a new behavior where the right half of the screen goes completely black and stays that way until I power cycle the tv. This usually happens once or twice a day and it is driving me nuts. Short of replacing the DMD board which isn't even available for purchase anymore on samsungparts is there another fix for this? I see that samsung is replacing defective dmd boards that have the white dot problem so is there any chance they would cover this design or manufacturing defect as well?