Second monitor weird colors unbuntu

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http://www.linuxquestions.org – Hi guys, My name is Reza & i am a newbie to linux,installed ubuntu just yesterday, at first with a single boot system(ubuntu) everything were fine with everything include second monitor ,then i installed vista too,now i have a dual boot system & i am very happy to get rid of crappy junk microsoft's software as much as i can,unbuntu performance is really wonderful to me,just i have one problem,my second monitor show very weird colors ,almost like a negative print,then i boot with vista & there everything are fine with my second monitor,then i guess i don't have any hardware or drive (HowTos)