Oh boy this could be a million different things...I'd try adjusting your sharpness in the menu options or picture quality. If that doesn't help then try a different cable to hook up to your monitor and computer or try a different adapter or different slot when plugging in the cable to your graphics card ( If you have a second slot). As a last resort take your monitor into a local shop ( make sure he knows what he's doing first! ) or get help from Samsung technical support either online or telephone. Samsung may possibly let you return it if you have a warranty on it. If that does not work then your outta luck as far as I know...Has this monitor ever worked before or has it been like this from day one?