报错：ROLLBACK TRANSACTION 请求没有对应 BEGIN TRANSACTION

C# code

        private static void Prepare(SqlConnection con, SqlCommand cmd, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)        {            con.ConnectionString = ConnectionString;            cmd.Connection = con;            cmd.CommandType = cmdType;            cmd.CommandText = cmdText;            if (cmdParms != null)            {                foreach (SqlParameter parm in cmdParms)                    cmd.Parameters.Add(parm);            }            con.Open();        } public static int ExecuteNonQuery(CommandType cmdType, string cmdText, params SqlParameter[] cmdParms)        {            using (SqlConnection con = new SqlConnection())            {                int iResult = -1;                SqlCommand cmd = new SqlCommand();                Prepare(con, cmd, cmdType, cmdText, cmdParms);                SqlTransaction tran = con.BeginTransaction();                try                {                    iResult = cmd.ExecuteNonQuery();                    tran.Commit();                }                catch                {                    tran.Rollback();                    throw;                }                return iResult;            }//end using        }

数据库是SQL Server 2000，368条Insert语句，每条语句12个字段。
之前插入都是正常的，今天突然就报错了。

[解决办法]
没改过代码的话，就是数据库问题。