Mavericks filevault stuck after login

Hi

I have just bought my macbook air 13" with mavericks, 8gb RAM, 256GB SSD.

I've enabled file vault, noted my recovery key and my machine has restarted. It then prompts me for my password, which I enter.

It then shows a no symbol (circle with diagonal line through it) and the spinning cog/progress circle in the middle of the screen.

It's been spinning around for about 45 minutes now, and am not sure what's going on.

Help. Has the encryption process failed? I thought it was supposed to dump me back to my desktop so I can view the encryption progress?

I've closed the lid on my mac, and the apple is still lit up.

Erm am I stuffed?