Navigation Pane keeps hidding

[Julie]

I go in the Access Options | Current DB | Display Navigation Pane, I check
this box, have to close and re-open, then fine I see the navigation pane.

Then, seems to be with no reason, the next time (or sometimes a few times
later )I open my project, it's hidding again, and the checkbox is unchecked,
so I have to to the same again.

Any idea how I can stop that ?

Thanks

Julie