I will upload the map, it seems to happen for a mate as well... After removing the items in the house on the hill (keep heading east from spawn) with MCEdit, its fine. So its one of the machines up there causing it.
Updated the server to 5.6 and it still happens with the machines there, removed them, its fine.
Map: https://dl.dropbox.com/u/62548886/FILES/SAVES/TEKKITLITE/0.5.5/world_dead_29-1-2013.rar