Thanks, yes I meant setting the Mesh name the same too... which I now won't try.
This all came about when I had all 3 Zone Directors with meshing enabled (different essids), and at some point, it seems, all the 100-odd access points started querying each other as to if they were a valid mesh AP, and it just ended up bringing down the entire network.
I think what I will do is turn on meshing on only one Zone Director (the 3000) and leave the others without meshing.