A family of Microsoft relational database management systems designed for ease of use.
RF12321,
Since it only appears on the Gantt Chart view, it sounds like that view is corrupt. Unless you have a lot of custom views, you could try re-setting your Global. To do that, close Project, find your working Global file, move it to the trash, and then re-start Project.
If you do have lots of custom views, tables, filters, etc., you could try deleting the Gantt Chart view in the Organizer (right side). That will give you the default Gantt Chart for that file.
John