Save Autorecover info saves also the stencils

[Yacine]

Does anyone know why Visio (2003 at least) saves all the stencils in use, even if they are not being edited, when you set the save autorecover option?
That's quite anoying when you use a larger number of stencils and set the time laps to a low value (15 min).
Any guess how this can be discarded?