My brother had that happen to him as well, I'm not ENTIRELY sure how t fix it? But I'd figure:
1) Restart your computer.
If that doesn't work,
2) Make sure you have the latest patch downloaded.
Sometimes I've gotten in without downloading the patch, but never made it to the pin page before getting booted. Then it worked.
3) Try uninstalling and reinstalling MS. Every MS Problem I've ever had that the first two steps didn't fix, this one fixed it.
Good luck with this, if my help doesn't work, someone will figure it out. :)