So, here's the scoop:
When you get your rice, there's a chance it may contain bacteria. When you cook it the first time round your bacteria will die but some will survive in the form of spores. If left at room temperature spores will germinate turning back into bacteria and producing toxins that make you vomit.
As far as I can see it's important to cool and reheat the rice really quickly(under an hour). This will prevent spores from germinating.
Ways to do this: Place newly cooked rice in a shallow pan and/or immerse in ice water to cool.
Reheating fast shouldnt be a problem in the microwave/grill however the rice must be reheated to at least cooking temperature, that is, around 70 degrees C.
Finally, cooked rice should be stored below 5 C, which we probably do anyway.
Officially more than day-old rice is bad and re-reheating is definitely a big no-no, as we know.
Unofficially, just make sure you minimize the amount of time the rice stays at room temperature and use it asap.
Also washing the rice well before cooking will help get rid of any initial bacteria.
That's the scoop on rice