A group of dissident stockholders, citing more than $30 million in losses over the past several years, seeks to replace the board of directors of Dairy Mart Convenience Stores and explore a possible sale of the company.The group, which calls itself the Committee of Concerned Dairy Mart Shareholders, is led by former Dairy Mart president and CEO Frank Colaccino.In a news release Wednesday, the group said it has filed preliminary proxy materials with the Securities and Exchange Commission and will launch the ouster effort at Dairy Mart's May 25 stockholder meeting."The company has posted losing years over the past six and seems to be well on its way to another disappointing performance, said Colaccino, who ran Dairy Mart from 1988 to 1994.Dairy Mart reported a net loss of $900 million, or 17 cents per share for the quarter ended Jan. 30.If the takeover is successful, Colaccino said the new board would explore the company's possible sale.A Message seeking comment was left Wednesday night at the company's Hudson, Ohio, headquarters, which was closed for the day.Dairy Mart owns or operates approximately 600 retail stores in seven Midwest and Southeastern states. The company was formerly based in Enfield, Conn.Shares of Dairy Mart were unchanged Wednesday at $3.37 1/2 on the American Stock Exchange.