Hello, could someone help recently i noticed white streaks coming from top left corner on my 21.5 inch mid 2011 iMac can only notice it when it is turned off but its bugging me i thought it might be dust or because i smoke a fair bit around iMac i removed the plastic over the Screen to clean it an the white streaks disappeared when i removed it so i guess the actual screen is fine? i then cleaned the plastic with an Iklear micro chamois cloth but soon as i put it back on the white streaks came back any ideas how i can get rid of the streaks? thanks in advanced.