Something non-conductive and that doesn't harbor static electricity.
I'd suggest a wood or fake wood laminate surface. Stone, tile or linoleum are good choices too.
However, DONT put it on the outside of something like those antistatic bags. The bags themselves are conductive and could mess your stuff up. Also, don't put it on any other sort of plastic or carpet or cloth.
EDIT: If it still doesn't post, try my previous suggestion of shuffling the ram to different slots