State health officials have threatened to force the closure of a grocery store in Mount Vernon following an inspection that found ?critical deficiencies? such as unprotected food, unclean shelves and evidence of rodent activity.The inspection by the state Agriculture Department was prompted by amateur video showing mice running over food packages and tearing through bags of chips and other snacks at the Show Place grocery on East Prospect Avenue.Inspectors issued a notice on the door Thursday and said the problems must be corrected or the store will be forced to shut down.For their part, the store?s owners insist they do not have a rodent problem.