Just bought my 2011 27" iMac yesterday, and when I start iTunes, it toally locks up the system, and the only way to gain control again is to turn off the power and reboot. The mouse moves around on the screen, but it's totally unresponsive to any clicks. Has anyone else had this issue?? I've seen some discusion threads about rebuilding the iTunes library xml, but that hasn't helped one bit. Neither has deleting and re-installing iTunes. This is absolutely frustrating! Let me add to this.....if i let it set long enough, I get a spinning pinwheel.