iCloud "You can't sign in at this time"

[PORANSINGH]

Alternative solution.

I had these same symptoms today (unable to log in to iCloud through System Preferences). However, I could connect just fine if I used a different user account on Lion (with the same Apple ID and password). I don't use Little Snitch and toggling the built-in firewall didn't help.

This lead me to the solution for my issue: deleting the ~/Library/Application Support/iCloud/Accounts folder.

excellent work, it worked perfect!! Thanks