Also ich möchte Tasten systemweit sperren.
Mein Quelltest (aus dem Beispiel)

unit1.cpp

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TKeyHookForm *KeyHookForm;

extern "C" __declspec(dllexport) __stdcall void SetHook(void);
extern "C" __declspec(dllexport) __stdcall void RemoveHook(void);
extern "C" __declspec(dllexport) __stdcall DWORD CheckKey(int, WORD,LONG);
//---------------------------------------------------------------------------
__fastcall TKeyHookForm::TKeyHookForm(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TKeyHookForm::KeyHook(TMessage &Message)
{
  char Key[80];
  GetKeyNameText(Message.LParam, Key, 80);
  NULL;
}
//---------------------------------------------------------------------------

void __fastcall TKeyHookForm::Button2Click(TObject *Sender)
{
RemoveHook();
Application->Terminate();
}
//---------------------------------------------------------------------------

void __fastcall TKeyHookForm::Button1Click(TObject *Sender)
{
SetHook();        
}
//---------------------------------------------------------------------------

keydll.dll

//---------------------------------------------------------------------------

#include <vcl.h>
#include <windows.h>
#pragma hdrstop
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
#define WM_KEYHOOK WM_USER+100
HHOOK ghhookKB;
HINSTANCE ghInst;
#pragma argsused
int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
        ghInst = hinst;
        return 1;
}
//---------------------------------------------------------------------------
extern "C" __declspec(dllexport) __stdcall void SetHook(void);
extern "C" __declspec(dllexport) __stdcall void RemoveHook(void);
extern "C" __declspec(dllexport) __stdcall DWORD CheckKey(int, WORD,LONG);
//---------------------------------------------------------------------------
void __stdcall SetHook(void)
{
  HOOKPROC lpfnHookProc = NULL;
  lpfnHookProc = GetProcAddress(GetModuleHandle("keydll.dll"),"CheckKey");
  ghhookKB = SetWindowsHookEx(WH_KEYBOARD, lpfnHookProc, ghInst, NULL);
}
//---------------------------------------------------------------------------
void __stdcall RemoveHook(void)
{
  UnhookWindowsHookEx(ghhookKB);
}
//---------------------------------------------------------------------------
DWORD __stdcall CheckKey(int nCode, WORD wParam, LONG lParam)
{
  HWND ghAppWnd = FindWindow("TKeyHookForm", 0);
  if((nCode < 0) || nCode == HC_NOREMOVE)
    return CallNextHookEx(ghhookKB, nCode, wParam, lParam);

  // Skip if it's a repeat
  if(lParam & 0x40000000)
    return CallNextHookEx(ghhookKB, nCode, wParam, lParam);

  // Send key information to the main window
  SendMessage(ghAppWnd, WM_KEYHOOK, 0, lParam);

  return CallNextHookEx(ghhookKB, nCode, wParam, lParam);
}
//---------------------------------------------------------------------------

unit1.h
[cpp]
//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
#define WM_KEYHOOK WM_USER+100 
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
//---------------------------------------------------------------------------
class TKeyHookForm : public TForm
{
__published:    // Von der IDE verwaltete Komponenten
        TButton *Button1;
        TButton *Button2;
        TLabel *Label1;
        TLabel *Label2;
        void __fastcall Label1Click(TObject *Sender);
        void __fastcall Button2Click(TObject *Sender);
        void __fastcall Button1Click(TObject *Sender);
private: // User declarations
  MESSAGE void __fastcall KeyHook(TMessage &Message);
    BEGIN_MESSAGE_MAP
      MESSAGE_HANDLER(WM_KEYHOOK, TMessage, KeyHook);
    END_MESSAGE_MAP(TForm);
public:     // Anwender-Deklarationen 
        __fastcall TKeyHookForm(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TKeyHookForm *KeyHookForm;
//---------------------------------------------------------------------------
#endif

[/cpp]

jedenfalls weiß ich nicht wie genau ich das jetzt machen soll, das die Tasten systemweit nicht mehr funktionieren.

Danke im Voraus

eventuell ist es mit hooks möglich, aber damit habe ich mich noch kaum beschäfftigt.

Wieso sollten die die davon Ahnung haben nicht darauf antworten? Habe ich etwas faölsch gemacht?