I still cannot understand the concept of castling in Chess960. When I play Rybka on my computer at Chess960, when I have not moved either of my rooks nor king, sometimes I can castle and sometimes I can't. Sometimes I'm not allowed to capture a piece with my king when it is completely legal to, that is not putting myself into check.

Can somebody please explain to me the rules and concept of castling in Chess960? If you can do a few diagrams that would be greatly appreciated as I am more of a visual learner. Thank you.

What is Chess960?

The castled king and rook land on the same squares as in regular chess, regardless of their starting position. All of the same castling rules apply -- the king cannot castle through check, cannot be in check, and all minor pieces must not occupy squares the king will castle through.

So in other words, castling king-side in Chess960, the King (white) would land on g1 and rook on f1, queenside would be King on c1 and rook d1.

Exactly. No matter where they start, they end up in the same place they normally would. They just have to be able to get there.

Thank you very much for your help "slack" and "ichabod801"!