I have spent hours searching for a solution to this, and have been unsuccessful. Because my setup is pretty basic, I cannot be the only one facing this, so I figured I'd post a thread about it. My setup: I have an iPhone 4 and a MacBook Pro. I have my original AppleID (@gmail.com) I have my MobileMe email address (@me.com) Per Apple's instructions, when I upgraded my iPhone 4 to iOS5 and subsequently set up iCloud, I entered my @me.com email address. This supposedly turned my @me.com address into an AppleID (whatever that means). Ultimately, my iPhone works fine, and is connected with iCloud. I also did the move from MobileMe to iCloud on the me.com website (which took me to iCloud.com). iCloud.com works fine, and is connected with iCloud. Finally, I went to my System Preferences in my MBP, and attempted to sign into iCloud using my @me.com ID, per Apple instructions. iCloud setup on my MacBook Pro (10.7.2) fails every single time, and gives me the following error message: Cannot Sign In: This Apple ID is valid but is not an iCloud account. Does anyone have any ideas what I can do to solve this problem? I called Apple support, and even their 1st-tier technician couldn't provide a solution. She said she escalated to a Senior Advisor, and that I'd have a call back in 24 hours, and that was about 30 hours ago. Oh well. Any help is appreciated.