The pilot reported that during the landing roll she had a difficult time slowing the airplane down and thought there might be a problem with the brakes. After overcorrecting with right rudder the airplane veered off of the right side of the runway, where it impacted a runway sign and a taxiway light before coming to rest upright. The airplane sustained substantial damage to the right wing's leading edge spar. A postaccident examination of the brake system revealed no evidence of a mechanical malfunction or failure that would have precluded normal operation.