We've had problems in the past where users that synchronized their local copies of Front Page (can also occur with Visual Interdev), and they had the privileges set differently local. The local settings end up overwriting whatever you had set up on the server.

Don't know if it's your problem, but someone using Front Page or Interdev either needs to have their rights restricted or take care that they don't go out and rearrange the server every time they sync up. Me, I don't like any web site authoring tools - preferring the simplicity of text editors and source control.