RegisterServiceProcess does pretty much what it sounds like. It registers a process as a "service process," a process which continues to run after the user logs off. A registered service process is exempt from automatic shutdown at logoff time. An added benefit of being a service process is that you are not listed in the tasklist. It is defined as:

DWORD WINAPI RegisterServiceProcess(DWORD procID, DWORD reg);

procID is the process id of the process to register (in this case, we use 0 to indicate the current process), reg is 1 for registering, and 0 for unregistering.

To do this trick, I made a function that loads the dll and registers or unregisters the process as a service process. I put this in the WinMain function of our app.

//--------------HiddenApp.cpp--------------
#include 
#pragma hdrstop

USERES("HiddenApp.res");
USEFORM("Unit1.cpp",Form1);


typedef DWORD (WINAPI *TRegisterServiceProcess)(DWORD,DWORD);
bool registered=false;

//-----------------------------------------------------------------------
void __fastcall reg(bool which) //true=register, false=unregister
{
  HMODULE hmod;
  TRegisterServiceProcess pReg;
  hmod = LoadLibrary("kernel32.dll");

  if (!hmod) return;
  (FARPROC)pReg = (FARPROC)::GetProcAddress(hmod,"RegisterServiceProcess");
  if (!pReg) {FreeLibrary(hmod); return;}
  else 
  {
    if (which)
      pReg(0,1); //unregister our process  
    else
      pReg(0,0);
  }
  registered = true;
  FreeLibrary(hmod);
}
//-----------------------------------------------------------------------
WINAPI WinMain(HINSTANCE,HINSTANCE,LPSTR,int)
{  
  try
  {
    reg(true);
    Application->Initialize();
    Application->CreateForm(__classid(TForm1), &Form1);
    Application->Run();
  }
  catch (Exception &exception)
  {
    Application->ShowException(&exception);
  }

  if (registered) reg(false);
  return 0;
}
//--------------eof--------------------------------------------------------