Either you are trying to restore state on a ROM where the state was auto saved under an older version of Emumaster, you you're save state is honest to god corrupted.

Either way, you should be able to bypass (and subsequently overwrite) the bad save state by clicking on the option to disable the auto state run.

I can't remember what the option is called and my N9 is not on me right now, but I remember the option was showed (I think) when long pressing on the game image before launching...