Hello everyone,

Just a follow-up to explain how I solved this problem. After doing some trial-and-error, I realized that the files installed in Program Files had read-write access. Therefore, upon opening these files Vista guessed I could write them and therefore made a copy into the virtual store. The solution was pretty straightforward: ensure the files have read-only attribute when they are installed. I just witnessed that with this attribute, virtual store files are not created anymore.

Thanks to you all for the pointers and tips. I'm really glad this major issue is solved.