Running external programs

Hi: I´m using PHP4 on IIS 5 on Windows 2000 Server and it works fine. The Microsoft NNTP Service from IIS 5 can be managed from command shell with commands like this bellow: cscript d:\\temp\\rgroup.vbs -t a -g new.group.01 And it works also fine in my system. But, when I try to run a program from a simple PHP script like the following: <? $commandstring = "cscript d:\\temp\\rgroup.vbs -t a -g new.group.01"; passthru($commandstring); ?> I get this Warning.. Warning: Unable to fork [cscript d:\temp\rgroup.vbs -t a -g new.group.01] in d:\inetpub\wwwroot\nntpadm\creategroup.php on line 3 What am I doing wrong? Thanks in advance.