When you close a Map or Browser window in MapInfo you are not necessarily closing the file. This can sometimes be confusing for those starting out with MapInfo as a GIS solution. When you click on the red X button, on the corner of the window in a word processing document or a spreadsheet, you can normally expect that the file is actually closed.
Joe Short BSc has been involved with various mapping solutions since 1993. If you are considering implementing a GIS or have ArcGIS, MapInfo or Quantum GIS training requirements I would be happy to be of assistance to your organisation.