The question on file DriverPack_Sound_B_wnt5_x86-32.ini is more exact on section [zU]
exc_1_command1 = "cmd.exe /c copy /y %DPSROOT%\D\S\zU\stlang.dll %SystemRoot%\system32"
exc_1_command2 = "cmd.exe /c copy /y %DPSROOT%\D\S\zU\ stacgui.dll %SystemRoot%\system32"
exc_1_command3 = "cmd.exe /c copy /y %DPSROOT%\D\S\zU\stacgui.cpl %SystemRoot%\system32"
Whence stacgui.dll undertakes? Simply curiously.