iBooks 3.1 keeps crashing after visual book shelf shows up

I upgraded my iPad 1 from 4.3.3 to 5.1.1, and also iBooks to the latest 3.1. I emptied all the books in my device, but iBooks keeps crashing just after the visual bookshelf shows up. I also tried re-install, restore settings and nothing turned out to be good.

Is there anyone knows how to fix this ? Or how to downgrade my iBooks?

Thanks!