From the Glossary of the living rules:
Unrest – Red disks representing Unrest are placed on enterprises by the play of certain Headlines, orange cards, and troops. For instance, the play of Yaqui rebels (even as a Private Army) places Unrest in all Sonoran enterprises (other than the one played into). If your enterprise has one or more Unrest, none of its Income, Extortion, Prestige, or Connection cubes earn gold, and its Prestige, abilities (e.g. the Chain Railroad ability), and Connection upgrade, as well as the Prestige on occupying troops, are inactivated. Remove Unrest with a “police action” (E8) or “redeploy troop action” (E5).