Thanks Radicalz38, that figures, I bought the 16GB card off ebay! Thing is, some of the MP4s play fine i.e. the first 9 episodes of the series play perfectly well, but all the others won't play! Seem to be having the same issue with my other 6GB card too - and I know that one's genuine.

Can anyone suggest the best place to buy a GENUINE 16GB micro SD card from?