That's no error message from the game itself, but from the copy protection. Since the requirement of administrator privileges is obvious, I guess you have tried that already. Must be Vista then, an operating system not in existence when the game was finished, so the copy protection couldn't bring along fitting drivers. If you install the current drivers, it should work properly. You can find them here ("2. Versions before 5.5", bottom of the page):http://www.star-force.com/support/drivers/
Just in case before the question "Why copy protect a demo?" comes up (happens every now and then): because an unprotected demo would have been an unprotected full version. The executables could have easily been modified and used with the full version, therefore the protection (only without DVD binding) for the build in demo limitations.