All, am new here, hello hello!

Hoping to get better advice here than I did putting this on technet.

The issue with my security is this:
- I have allowed user1, user2 and user3 access to a folder under a public share.
- Only user1, user2, user3 can open the folder
- Other users receive access denied - that works fine
- But other users can still blindly drag 'n' drop another folder/file into the restricted folder by simply clicking yes to a prompt
"Are you sure you want to copy or move files to this folder?" Click Yes and it moves it into the restricted folder.

I can't seem to replicate the issue anywhere else.

Ideas?