为什么Get-ChildItem命令不能从C#程序读取C盘？

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string[] files = Directory.GetFiles("C:\\");
        foreach (string file in files)
        {
            Console.WriteLine(file);
        }
    }
}

using System;
using System.IO;
using System.Runtime.InteropServices;

class Program
{
    [DllImport("shell32.dll", SetLastError = true)]
    static extern bool IsUserAnAdmin();

    static void Main()
    {
        if (!IsUserAnAdmin())
        {
            Console.WriteLine("请以管理员身份运行程序！");
            return;
        }

        string[] files = Directory.GetFiles("C:\\");
        foreach (string file in files)
        {
            Console.WriteLine(file);
        }
    }
}