It is possible to set a password for a VBA project.
It is also possible to get around this.
See: http://datapigtechnologies.com/blog/index.php/hack-into-password-protected-vba-projects/ (local mirror)
- Use a hex editor
- Search for DPB and change the B to an X.
- Save. Re-Open.
- Set password to a new one in VBA
- Open hex editor, change DPX back to DPB.
Forward and back a few times. Should work ok.