Hi John,
Thank you for contacting National Instruments.
What do you mean when you say that you did not lose any columns? If you are trying to programmatically set the number of visible columns in the table, then David's suggestion is valid. Are you resizing the table while the VI is not running? If you can clarify your question a little more, it will help me ensure that you find the answer that you are looking for.
Matthew C
Applications Engineer
National Instruments