Ok so my dad has just bought a MBA got it all going yesterday after a few migration issues. Just installed 10.5.2 all went ok. It asked to restart. I clicked yes and it hung on a blank screen. After about 10 minutes I manually shut the machine down. When i turned it back on i logged into his account (firevault is on) and it went straight into Welcome to Mac please register new user screen. Could not understand why it was doing this but followed the process through until the end. It then looped straight back round to user log in screen. Log in and same thing happens again!!! Whats happened??