Mysterious Multi-Restart Logins Plague File Vault MacBook Users
MacBook users are reporting that they are experiencing an issue after installing full disk encryption using File Vault. The problem manifests itself by automatically restarting the MacBook after it is turned on and restarted once already forcing the user to login twice before actually reaching their desk top.
Although the problem doesn’t seem wide-spread it is an interesting one that I am also experiencing on my MacBook Air. A discussion, Why does Lion immediately reboot with FileVault Enabled?, on Apple’s Support Community forums describes the problem.