Can you review my small project on bitbucket? [closed]

Question

My project is in here. This application shows status of capslock,numlock and scrolllock on the screen. Sometimes while it is running, my computer freezes.

//Program.cs
using System;
using System.Windows.Forms;

namespace Indicator
{
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    using System.Threading;

    using Timer = System.Windows.Forms.Timer;

    static class Program
    {
        private const int WH_KEYBOARD_LL = 13;
        private const int WM_KEYDOWN = 0x0100;
        private static LowLevelKeyboardProc _proc = HookCallback;
        private static IntPtr _hookID = IntPtr.Zero;
        private static Popup form2;
        private static Timer timer;

        [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true,
    CallingConvention = CallingConvention.Winapi)]
        public static extern short GetKeyState(int keyCode);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int idHook,
            LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool UnhookWindowsHookEx(IntPtr hhk);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode,
            IntPtr wParam, IntPtr lParam);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string lpModuleName);

        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            _hookID = SetHook(_proc);
            form2 = new Popup();
            timer = new Timer { Interval = 2000 };
            timer.Tick += timer1_Tick;
            Application.Run();
            UnhookWindowsHookEx(_hookID);
        }

        private static void timer1_Tick(object sender, EventArgs e)
        {
            timer.Stop();
            form2.Opacity = 0.9;
            for (double i = 0.9; 0 <= i; i -= 0.02)
            {
                Thread.Sleep(10);
                form2.Opacity = i;
            }

            form2.Hide();
            form2.Opacity = 0.9;
        }


        private static IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using (var curProcess = Process.GetCurrentProcess())
            using (var curModule = curProcess.MainModule)
            {
                return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
            }
        }

        private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)
            {
                int vkCode = Marshal.ReadInt32(lParam);
                if ((Keys)vkCode == Keys.Capital)
                {
                    var CapsLock = (((ushort)GetKeyState(0x14)) & 0xffff) != 0;
                    timer.Stop();
                    timer.Start();

                    form2.label1.Text = CapsLock ? "CapsLook Kapalı" : "CapsLook Açık";
                    form2.Show();
                }
                else if ((Keys)vkCode == Keys.NumLock)
                {
                    var NumLock = (((ushort)GetKeyState(0x90)) & 0xffff) != 0;
                    timer.Stop();
                    timer.Start();

                    form2.label1.Text = NumLock ? "NumLock Kapalı" : "NumLock Açık";
                    form2.Show();
                }
                else if ((Keys)vkCode == Keys.Scroll)
                {
                    var ScrollLock = (((ushort)GetKeyState(0x91)) & 0xffff) != 0;
                    timer.Stop();
                    timer.Start();

                    form2.label1.Text = ScrollLock ? "ScrollLock Kapalı" : "ScrollLock Açık";
                    form2.Show();
                }
            }

            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }
    }
}

---

//Popup.cs
namespace Indicator
{
    using System.Windows.Forms;

    /// <summary>
    /// The form 2.
    /// </summary>
    public partial class Popup : Form
    {
        public Popup()
        {
            InitializeComponent();
            Top = 50;
            Left = 50;
        }
    }
}