Posted by me today in PSO forums in answer to one of the THOUSANDS of "Online Poker MUST be rigged, because I got a bad beat" threads.
When you have setbacks, you can assume that one of three things happened.
1) You played poorly.
2) You got unlucky.
3) The game was rigged against you.
Idiots assume number 3, bad players assume number 2, and good players assume number 1.
The reason that good players believe number 1 is that even if number 2 is true, it doesn't do them any good. If you always assume that you can improve your game and you constantly try to do it, you will be better off.