The problem isn't the checksum algorithm, it's that TCP/IP only protects packets in-flight. The checksums aren't kept on-disk, so errors can creep in after they

The problem isn't the checksum algorithm, it's that TCP/IP only protects packets in-flight. The checksums aren't kept on-disk, so errors can creep in after they've made it across the network. Well, and also TCP/IP checksums are small enough that you'll relatively frequently see errors sneak through them. But that's not likely to be what you were noticing.