I've searched for it but I only found contradicting answers from "scientists":
Mr. David Balson, Ph.D. states: "entropy in a system can never be equal to zero".
Mr. Sam Bowen does not refutes the following affirmation: "It is know[n] that entropy is zero when a pure crystalline substance is at absolute zero". He says there's residual motion in particles, but he doesn't say clearly that 0 entropy isn't possible.
I this link is a long discussion about that, it isn't really conclusive, but most people seem to agree that entropy can be zero.
I'm not very receptive to the idea of zero entropy.