You're right, the command line was wrong, but that's doesn't change the problem. I get an office 2003 version, the service pack and some hotfixes and generate an DVD Image with your office slipstreamer 1.6.2 In the next step I've burned it to an DVD-R. And now the testcase: I've put this DVD in the DVD drive (drive d: in my virtual PC) and starts a command shell (cmd.exe). If I use the command shell (or change with c: to the first hard drive) than I get the wrong result. If I change the current drive ( with the input d: on the DOS prompt) to the DVD than the commandline from my prvious posting works. It looks for me, that your setup searched the orginal MS Setup-Programm on the current drive. If I don't change the current drive your programm looks at c: where isn't any orginal setup programm. If I chnage to d: before I call your setup, then your setup looks for the orginal on drive d:. And found it. Can you check the function (inside your setup programm), which builds (or expand) the commandline for the call of the orginal setup programm. Maybe you forget to forward the drive letter, maybe. PS: For your information: I work since over 20 years as a system analyst and senior developer with DOS, Unix and some other operatin systems. Pls apologize me if I use the terminology for DOS or win32 developer without to declare them.