It is possible that the network packets from the server to your client, which tell about the existance and attributes of the preparation table, went missing while the client was too busy doing something else, or the internet delaying some of them too long.
Leaving the game and restarting it might help.
Passing a map loading portal should help; maybe just walking to an area where you can't see this area for sure helps already too (e.g. down into Jirosh's warehouse and back to Brado's tavern).
And finally, be sure to run the updater sometimes (at least monthly).
