C# File Delete Bug in .NET

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using IWshRuntimeLibrary;

namespace test
{
    public partial class TestFileDelete : Form
    {
        Boolean flag = true;

        public TestFileDelete()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            // disables while running click code
            this.button1.Enabled = false;

            // This doesnt seem to do anything either?
            if (this.button1.Enabled == false) return;

            // just a either or flag to swtich the end of the shortcut names to see if they are deleted or not with one button
            int switchnum = (flag) ? 1 : 0;
            int newnum = (flag) ? 0 : 1;
            if (flag == true)
            {
                flag = false;
            }
            else
            {
                flag = true;
            }

            // this is a bit messy, its taken from my larger project. but this code shows my problem. (in fact my larger project only requires a 200ms timeout, this needs 300..?)
            String StartMenuProgName = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonStartMenu), "Programs", "skbt config", "config " + newnum);

            Dictionary<UInt32, String> Shortcuts = new Dictionary<uint, string>() {
                        {0,Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Start Keepalive (" + "config " + newnum + ").lnk")},
                        {1,Path.Combine(StartMenuProgName, "Start Keepalive.lnk")},
                        {2,Path.Combine(StartMenuProgName, "Auto Restart Test.lnk")},
                        {3,Path.Combine(StartMenuProgName, "Manual Restart.lnk")},
                        {4,Path.Combine(StartMenuProgName, "Manual Start.lnk")},
                        {5,Path.Combine(StartMenuProgName, "Manual Stop.lnk")},
                        {6,Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "README.txt")}
                    };
            foreach (KeyValuePair<UInt32, String> shortcut in Shortcuts)
            {
                while (System.IO.File.Exists(Path.GetFullPath(shortcut.Value.ToString())))
                {
                    // Will only delete with a delay of at least 300 ms.????
                    if (this.checkBox1.Checked == true)
                    {
                        Thread.Sleep(300);
                    }
                    System.IO.File.Delete(Path.GetFullPath(shortcut.Value.ToString()));
                }
            }
            if (Directory.Exists(StartMenuProgName)) { Directory.Delete(StartMenuProgName, true); }


            // Current Name
            StartMenuProgName = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonStartMenu), "Programs", "skbt config", "config " + switchnum);

            // Create Shortcuts on desktop / add to programs start menu
            String BatchLibPath = @"c:\test";

            if (!addShortcut(
                Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Start Keepalive (" + "config " + switchnum + ").lnk"),
                Path.Combine(BatchLibPath, "start_keepalive.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (0).");
            }

            if (!addShortcut(
                Path.Combine(StartMenuProgName, "Start Keepalive.lnk"),
                Path.Combine(BatchLibPath, "start_keepalive.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (1).");
            }

            if (!addShortcut(
                Path.Combine(StartMenuProgName, "Auto Restart Test.lnk"),
                Path.Combine(BatchLibPath, "control", "auto_restart.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (2).");
            }

            if (!addShortcut(
                Path.Combine(StartMenuProgName, "Manual Restart.lnk"),
                Path.Combine(BatchLibPath, "control", "manual_restart.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (3).");
            }

            if (!addShortcut(
                Path.Combine(StartMenuProgName, "Manual Start.lnk"),
                Path.Combine(BatchLibPath, "control", "manual_start.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (4).");
            }

            if (!addShortcut(
                Path.Combine(StartMenuProgName, "Manual Stop.lnk"),
                Path.Combine(BatchLibPath, "control", "manual_stop.bat")))
            {
                MessageBox.Show("There was an error creating a shortcut in the Start Menu (5).");
            }
            this.button1.Enabled = true;
        }

        private static Boolean addShortcut(String ShortcutPath, String TargetPath)
        {
            try
            {
                WshShell shell = new WshShell();
                IWshShortcut link = (IWshShortcut)shell.CreateShortcut(ShortcutPath);
                link.TargetPath = TargetPath;

                if (!Directory.Exists(Path.GetDirectoryName(ShortcutPath)))
                {
                    Directory.CreateDirectory(Path.GetDirectoryName(ShortcutPath));
                }
                link.Save();

                return true;
            }
            catch
            {
                return false;
            }
        }

        // Does Nothing when used in that loop.
        protected virtual bool IsFileLocked(FileInfo file)
        {
            FileStream stream = null;

            try
            {
                stream = file.Open(FileMode.Open, FileAccess.ReadWrite, FileShare.None);
            }
            catch (IOException)
            {
                //the file is unavailable because it is:
                //still being written to
                //or being processed by another thread
                //or does not exist (has already been processed)
                return true;
            }
            finally
            {
                if (stream != null)
                    stream.Close();
            }

            //file is not locked
            return false;
        }
    }
}