Screen flickering with lines !!!

Hi, I purchased a new lenovo g50-70 laptop 1 month ago..from the second day itself its getting blue screen error...i went to the shop where I purchased and he said that it is OS problem and he re installed the OS and gave it to me even though the problem continued like this only...after a 6 times OS reinstallation I wexed with his words and I went to lenovo service center..there they also checked whole system and said that there is no hardware problem..finally I understood that it is drivers problem..so I updated all from the official site..i'm having 2gb AMD graphic card..after updating drivers also after 2 days its again showing the screen flickering lines...how to solve this problem..??how to adjust the graphic settings without hanging?in which resolution I have to keep my graphic card without strucking like this??please help me out...i'm facing alot of problem with new laptop..please please...thank you in advance..