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You can start by uninstalling and reinstalling your syncmaster drivers again.
Also do the same for your video/graphics display drivers
If this does not work then you will need to contact samsung for repair of it, this is a common known problem with that model.
Well the reason I said to first reinstall the driver is because that sometimes cures the problem, you should have received an install disc with the display. If the driver does not cure the problem in your case it may be better to just replace it then.