Disabling the Alt-Tab key combination

// Call the RegisterHotKey function when the application 
// is instantiated to block the ALT-TAB combination
// Note:  The m_nHotKeyID is a int which specifies the hotkey 
//        ID, the hotkey id is programmer defined
CMainFrame::CMainFrame()
{
 m_nHotKeyID = 100;

 BOOL m_isKeyRegistered = RegisterHotKey(GetSafeHwnd(), m_nHotKeyID,
  MOD_ALT, VK_TAB);

 ASSERT(m_isKeyRegistered != FALSE);
}


//lets remove the hotkey block when the application is destroyed
CMainFrame::~CMainFrame()
{
 BOOL m_iskeyUnregistered = UnregisterHotKey(GetSafeHwnd(), m_nHotKeyID);
 ASSERT(m_isKeyUnregistered != FALSE);
}

One last thing, the hotkey block will continue as long as your application is running. When your process terminates the hotkey will return to its original functionality.