After I have downloaded OS x Lion and updated the software, I am not able to login to icloud from my Mac. I just get the error message “Account limit reached”. I have multiple accounts on my Mac and I want an icloud account for all users.

Windows Live offers 25G per person and does’t limit them, but Apple only limit 3 accounts per device with only 5 gb. If you have reached the limit, you can replace the serial number in the smbios.plist and it will work. And you can also submit a request with the iTunes Express Lane for Apple to give you one more account.