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Message: [QUOTE="abc_giligil, post: 14119656, member: 113414"] Hi, I'm building a program that at some point needs to hook the keyboard input to prevent the user from pressing some key combinations. Then, at a later point I need to unhook the keyboard, and then, I need to hook again the keyboard. I succeed in hooking the keyboard for the first time and then unhhok the keyboard, but when I try to hook it again using the same code, it seems that the hooking-method is not called at all, although 'SetWindowsHookEx' method succeeds. Here is how I do it: First, declarations: [DllImport("user32", EntryPoint = "SetWindowsHookExA", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall, SetLastError = true, ExactSpelling = true)] private static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, int dwThreadId); [DllImport("user32", EntryPoint = "UnhookWindowsHookEx", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall, SetLastError = true, ExactSpelling = true)] private static extern int UnhookWindowsHookEx(int hHook); [DllImport("user32", EntryPoint = "CallNextHookEx", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)] private static extern int CallNextHookEx(int hHook, int nCode, int wParam, IntPtr lParam); private static int LowLevelKeyboardProc(int nCode, int wParam, IntPtr lParam) { ... return CallNextHookEx(intLLKeyboard, nCode, wParam, lParam); } private delegate int HookProc(int nCode, int wParam, IntPtr lParam); private static HookProc KeyboardDelegate = null; //Static member private static int intLLKeyboard = 0; //Static member Then, setting the hook: KeyboardDelegate = new HookProc(LowLevelKeyboardProc); System.Reflection.Module[] modules = System.Reflection.Assembly.GetExecutingAssembly().GetModules(); intLLKeyboard = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardDelegate, System.Runtime.InteropServices.Marshal.GetHINSTANCE(modules[0]), 0); Later, unhooking : UnhookWindowsHookEx(intLLKeyboard); Then, trying to hook again : KeyboardDelegate = new HookProc(LowLevelKeyboardProc); System.Reflection.Module[] modules = System.Reflection.Assembly.GetExecutingAssembly().GetModules(); intLLKeyboard = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardDelegate, System.Runtime.InteropServices.Marshal.GetHINSTANCE(modules[0]), 0); At this point 'intLLKeyboard' is not null, but nevertheless, it seems that the hooking procedure isn't called at all. [/QUOTE]

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