Problem Activation of Filevault2

Hi!

I have tried to activate the new Lion's FileVault2 in my MacBookPro, but I'm experiencing some strange issues...

After the activation process (save the key, reboot, etc..) Lion started the encription of the disk but after a while it stopped and said "error in the disk. repair the disk and reboot". Strange! I had repaired disk and permissions before upgrade, but.. anyway... I did it.

And from there the trouble started: after the reboot filevault continue saying "error in activation, please deactivate filevault", but if I try it goes in loop and say "Impossible deactivate filevault. Error. Please repair the disk and try again". Disk Utility keep saying the disk is ok.

Any ideas?

(Sorry, the language of the screenshot is not english...)