how to know who is accessing my system?

fsmgmt.msc is your friend. Run this on the workstation in question and you will be able to see all shares, sessions, and open files on that particular workstation. From this utility you will be able to close any particular session and with folder permissions you should be able to restrict usage. However, it really depends on the privileges of the connecting user in question as to whether or not you can keep them out in this fashion. For instance, if the user is a domain admin.

Anyhow, I believe that fsmgmt will definitely get you moving in the right direction. Please write back and let us know how you made out!

Good luck.

You can go to "Computer Managment" and under to system tools you have Shared Folder, Tere You can see some basic information. To open Compute Managment on icon MY Computer right click and chose Manage