Each time one navigates to the User Administration page a new UserAdminController is created, but only the first one's driver gets initialized properly because of the static CRUD table widget. This may also happen for other controlled objects.
Trac #399.
From Trac #400. Each time one navigates to the User Administration page a new UserAdminController is created. Each one registers itself with the static CRUD table widget, so each one stays in memory and is called when the CRUD table widget is updated. This is why Trac Ticket #399 happens. This may also occur for other controlled objects (like projects).