I think you should rebuild your server. Something in the coding is broken. Minecraft thinks that when you suddenly move to another spot like that you "fall" so it kills the player. I would fix this by taking off your worlds and other critical things like plugins if you have any and delete your server.jar or bukkit.jar. Then put the save and plugins back on. If this doesn't help then I'm very sorry for wasting your time.
*remember to backup the entire thing befor you do this incase of a full meltdown of the server after attempted recovery*
