Dear fellow members, a few weeks back i bought a splendid i7 imac 27" via apple. After a few weeks of usage i realized that there were dark areas ( http://img90.imageshack.us/img90/5365/bild2bm7.png ) building up in the upper third of the screen. Called Apple Care - replaced the lcd - now it is perfect again .. let's see for how long ... Anyway - i was wondering what diagnostic utility do those apple reseller techs use to verify a screen/lcd problem since they were not able to login to the OS itself ?!?