ASP usually is denied access to anything potentially dangerous, such as cmd.exe. Check file permissions on cmd.exe to see if that is true for you (I suppose it is).
If you really must use cmd.exe to do part of the page processing, either change file permissions on cmd.exe (not recommended for an Internet-facing web-server), or make sure that the ASP page runs credentials that are not denied access to that file.
To achieve this, use the IIS management console to remove "anonymous access" to the ASP page and use Windows-integrated authentication instead (if feasible), or leave "anonymous access" on and enter a fixed set of credentials that should be used instead of the default "IUSR_...".
Alternatively, if you use cmd.exe just to start a program that outputs something to STDOUT, you can try starting the program directly, without wrapping it in a cmd.exe call. Again, the user the ASP page runs under needs access to that program's executable.