Producer Beth Sullivan has been sued by her former agent for allegedly failing to pay commissions on projects including the new CBS series “Dr. Quinn, Medicine Woman.”Artists Agency Inc., which does business as Favored Artists Agency, claimed in a complaint filed in Los Angeles Superior Court that Sullivan unilaterally terminated management and representation contracts in August 1991 although they were to run until November 1992. The agency says it negotiated with CBS on “Dr. Quinn” and also got Sullivan other employment. The contracts called for the agency to get 10% of Sullivan’s gross on projects obtained during the contract period and within six months of its expiration. Suit seeks unspecified damages.