Thread: looping within a wParam/notification

I'm trying to get the program to loop within a case, and stop if another case happens. So far it works ok for a couple seconds, then it freezes and crashes. It also freezes (not responding) if I click away from notepad, and try to focus my program again. All it does for now is alternate between typing '2' and '3' in notepad. I don't how to go about fixing it so the program does not "not respond" when i try to focus it while it's typing in notepad. Using Devcpp compiler

Code:

case FILE_START:
{
     HWND Handle = FindWindow(NULL, "Untitled - Notepad");
     if(SetForegroundWindow(Handle)){
          SetFocus(Handle);
                    		
          Sleep(1000);
          INPUT inputf1, inputf2;

          ZeroMemory(&inputf1, sizeof(INPUT));
          inputf1.type = INPUT_KEYBOARD;
          inputf1.ki.wVk = VK_NUMPAD2;
							
          ZeroMemory(&inputf2,sizeof(INPUT));
          inputf2.type = INPUT_KEYBOARD;
          inputf2.ki.wVk = VK_NUMPAD3;
							
          while(wParam != FILE_STOP){
               Sleep(500);
               SendInput(1, &inputf1, sizeof(INPUT));
               Sleep(500);
               SendInput(1, &inputf2, sizeof(INPUT));
          }							
     }
}
break;