The default c-treeACE SQL JDBC socket timeout has been changed from 30 minutes to 0 (no timeout). This timeout can be modified by setting the sock_timeout property explicitly at connection time:
Properties info = new Properties();
info.setProperty("user","ADMIN");
info.setProperty("password","ADMIN");
info.setProperty("sock_timeout","30000");
conn = DriverManager.getConnection ("jdbc:ctree:6597@localhost:ctreeSQL", info);