safe_mode and exec() in win2003 server

Hi, sorry if this question has been posted, but my search was unsuccessful. My environment: win2003 server, apache 2.0.54, php 4.3.11 When safe_mode is off, calls to exec() go just fine; when safe_mode is on and safe_mode_exec_dir is set properly, calls to exec() does not show the expected result, but php says otherwise: return code is 0, no error/warning is shown, even with error_reporting(E_ALL). I tried to allow IUSR_MACHINENAME to execute C:\WINDOWS\system32\cmd.exe, to copy cmd.exe to C:\PHP, to start Apache not as 'local system account', to call cmd.exe /C my_executable, to exchange '\' by '/' and vice versa, but no success at all. Any help is appreciated, thanks in advance, Zagab