Macbook Pro 13 issue ( with screen or maybe graphic)

[Aznprid3]

I just got my macbook pro 13" for about 2 months and i was happy with it but somehow lately the screen keep having black line running across from one side to another side or sometime on the website I'm browsing such as utorrent.eu , rapidshare and etc. It really strange when i send to the the place i bought my macbook it say " there no issue , everything is fine" but when i got home it keep occuring again and again. Make it more simple (e.g when we use a normal computer and you have your phone next to you and when somebody about to call you the computer screen start shaking)... It similar to that but it strange how i never have my phone or anybody phone close to my laptop. I'm really curious and sick of keep going back to the store. Is anybody have any idea or similar problem to mine? or any suggestion or way to solve this issue because it killing my eyes when i stared at the screen. I hope you guys can help me. Thank you !