Same with me. After my .mac-account was moved to iCloud, I seem to have two identities, one from my .mac history, the second my Apple-ID through which I came to .mac. Each time my machine is booted, it has a problem with my Apple-ID. Then I read that the second one was not my primary iCloud account. Well, what to do? I tried to delete the synchronisation of my calendar with the "not-so-primary" account. All my entries that have been made on my Mac are deleted. I have never asked anyone to take my entries on a cloud and to keep them there.
How can I get off that cloud?