Problem accessing Local Activation Permission for Application

[ElGordo]

I have a .Net application which includes a function to open a command shell
and run an executable (for a file extraction program, 7zip).

I can run the same exact command line manually with no problems. I noticed
that each time the same command line statement is run from the .Net
application (always unsuccessfully), an event is logged in the event viewer
stating:

______
The machine-default permission settings do not grant Local Activation
permission for the COM Server application with CLSID
{CLS-ID}
to the user ASPNET SID (ID). This security permission can be modified
using the Component Services administrative tool.
______

The CLS-ID references that of the command line program I execute (the file
extraction utility).

However, when I try to grant this program the appropriate permissions in
Component Services / DCOM Config, the program isn't listed!
Does the error mean that the ASPNET user account cannot execute the program?

If so, how can I remedy this if XP does not even list it in the DCOM Config
UI?

Should I be looking somewhere else?
Help!
Running: XP Pro / SP2