"Warren" wrote...
The reason I want to do this is this: after the file has been 1) loaded
onto the target PC harddrive AND 2) opened, if the file is then copied
to someone else's PC, it will not be fully functional because I want the
progam (VBA) to determine that it has already been opened. If it does
determine that, it will render the spreadsheet less than fully functional.
....

If you just want to discourage file copying, original distribution with
static password protection should be sufficient. That'll be enough to
prevent unsophisticated users from altering your file. As for sophisticated
users, take a look at all the responses in the Excel newsgroups about
available passwork crackers. It'd take maybe 2 seconds to remove all the
dynamically created random passwords you're thinking about adding. 2
seconds! After which time it'd be child's play to search & destroy all the
protective macro code you think is protecting your model.

Final comment: just speaking for myself, I don't think any software
distributed as Excel files is worth anything. Either you're providing a
service of some worth, and all files including .XLS ones are merely adjunct
to the service, or you're providing a product, in which case .XLS file
distribution isn't exactly the hallmark of professional development.