I recently had the misfortune of one of my ‘colleagues’ downloading some software to crack the password protection on the VBA modules included in a database I’ve built, and then, doing quite a bit of s*** stirring because of a couple of little insurance policies I’d included in the code (nothing malicious, just little friendly reminders on certain dates).
First, the 'insurance' policies you mentioned could not possibly cause any stirring unless they did something that might have been considered ethically questionable or non-trusting. I make no accusations, but I will offer these thoughts.
Did you encode a back-door? Many companies would consider (rightly so) that exposing a back-door personal to you would actually be GOOD for the company because you should not have one of those without proper authorization. Even if it is your project (see below about ownership issues).
Was it something that would tweak someone who didn't behave? You have to be careful because what you are doing might not be within security policies in your company. Tweaking might be wrong. Automatic e-mail reporting to your security persons might be the proper response.
suggestions as to how I can protect my code from prying eyes in future.
Other posters have commented on Workgroup security as part of the problem. I most heartily agree. However, you have another issue that no one has discussed yet. What is company policy on cracking of the product? What status, if any, did the product have within the company?
Where I am going with this is simple.
If the s***-stirrer cracked your personal project and that product is not marketed by the company (and maybe isn't even officially recognized by the company), then basically you might have no recourse.
If the company recognizes this project officially, they may have a policy regarding hacker/cracker attackes on company products.
There is also the issue that anything you do on company-owned computers is the property of the company. It might actually have been ILLEGAL for you to encrypt that code without permission.
Finally, some companies have been known to make it an "instant firing" offense to have a password cracker loaded to a company machine. To know this, you need to know company policies on the subject.
I understand your indignation, perhaps even sympathize with it, but before you decide where to go next, make sure your indignation is not misplaced. If you don't start from the company policies on computer security, you are going nowhere with no legs to stand on.