I've had quite a few occurances - mainly when overly tierd. It can be freaky and not too many people suffer from it apparently (on a percentage basis).
Best thing is to just wait for your body to kick in rather than try and force movement - the episodes seem to pass more quickly for me anyway if I just wait patiently for my body to come online.
Just having this for a few minutes makes you realise how terrible it must be to be truly paralyzed.
Still, at least now I know some fellow gamers suffer from this and won't feel quite so alone next time I'm lying temporarily paralyzed in bed...
Try to be reasonable... its easier than you think...