Here is how to prevent that from happening.
1. Right click on the folder that you want to protect
2. Click on properties
3. Click on Netware Info tab
4. Put check mark on "Rename Inhibit" and "Delete inhibit"
5. Click on apply and OK
Also the command line can be used on OES11 server:
root# attrib /folder/protected_from_rename_delete_etc -s=ri,di