MacOS – MBP will reboot after unlocking filevault partition

Due to the limitations, you might want to use an encrypted disk image rather than whole disk encryption.

Come to think of it - why not use both?

You could always turn off FileVault if you felt it too much a hassle, but to get around the limitation you caught (thank goodness you did catch it), consider using Disk Utility to make secure the parts of your data you need to force into a locked state when that disk image is unmounted. This will let you sleep your mac and not compromise that data by allowing it to be re-mounted without the appropriate passcode being supplied.

You should be able to unlock or decrypt your FileVault 2-encrypted HD with Disk Utility. I've got a post on how to do this:

Using Disk Utility to unlock or decrypt your FileVault 2-encrypted boot drive:

http://derflounder.wordpress.com/2011/11/23/using-disk-utility-to-unlock-or-decrypt-your-filevault-2-encrypted-boot-drive/

If unlocking via Disk Utility isn't working, you may need to use your recovery key. I've got another post on how you can unlock using your recovery key using the command line:

Unlock or decrypt your FileVault 2-encrypted boot drive from the command line:

http://derflounder.wordpress.com/2011/11/23/using-the-command-line-to-unlock-or-decrypt-your-filevault-2-encrypted-boot-drive/