>I've just tried running two sessions of the Project Manager sample application on my PC, besides an annoying message about File Access Denied (due to both sessions trying to use the same resource file), both sessions run OK.
>

The Project Manager is an single user application.
That is why there are programs like MS Visual SourceSafe
that allow multiple developers to work on one project
at the same time. There are a number of these
programs out there.