In case of questions where the bounty amount expires, I believe the bounty is supposed to be given to the highest voted answer after the bounty was announced, with atleast 2 upvotes.

However, how does it work if no such answer was created?

I am specifically asking w.r.t this question

https://superuser.com/questions/211582/unable-to-install-windows-xp-blue-screen-error-pops-up-before-starting-windows/213362#213362

where the bounty was awarded to harrymc whose answer was 1 hour before mine, both have 2 upvotes and both were posted before the bounty.

However, the bounty was awarded to harrymc. whats the reason behind that?