>I have table buffering set to 5 but when I issue TableUpdate(.T.,.T.,MyTable) it returns true, but the table is not really updated. The values in the fields are not changed. They are changed on the screen by editing, and the tableupdate returns .T., but the physical table is not changed.

Make sure that "Send SQL Updates" checkbox is checked in the view designer on the 'update critera" tab.
..same thing as like DBSetProp(myView,"View","SendUpdates",.T.)