You can freeze it but need to be v careful, as Picante says it is a common source of food poisoning. It's to do with spores and a bit dull so won't go into it. If you don't want to chuck it away, cool it down as quickly as poss- cold running water or an ice bath is good- then freeze straightaway. When you want to use it, make sure you get it piping hot (above 75C to be exact) and throw away what you don't use. Definately don't reheat again though.
the important thing is not to leave it sitting at room temperature too long as bacteria in the rice can start to multiply and produce toxins. These toxins arent destroyed by heating and can cause food poisoning. The best thing to do is cool as quickly as possible and then freeze in portions. I'd defrost in the fridge before heating or use a microwave on the defrost setting and then cook to piping hot.