The table being loaded into memory has a user-defined data type that is not recognized.

The table you are loading into memory refers to a recently created user-defined data type, but your in-memory list of user-defined data types does not include it.

Because the data type was created recently, it is not present in local memory.  All user-defined data types are loaded from the database into local memory when you open the first Table Designer window or database diagram within your connection to that database.  To refresh your in-memory copy of the database's user-defined data types, close all open database diagrams and Table Designer windows within that database connection.  After you close them all, reopen them in turn.  When you reopen the first one, the list of user-defined data types will be refreshed.

For more information, see Multiuser Environments.