Question about saving Internet Filtering rules

In the "Internet Filtering" tab, when click "save" button, a prompt appears, reading "Unable to write to ......Please check the file is not read-only". see the image from attachment. The destination folder is actually not read-only , and the LNS have been working well for a long time until this problem happened. When using the "Save as button" and saving to another path, the problem remains the same. What may be the cause? So much thanks for your help soon!

 

This is the standard message when it fails to create the file (with fopen function).
There is probably something preventing the program to create the file there.
It could come from another security program, or Windows itself. If you are under Vista, you could try to start Look 'n' Stop as administrator.

Regards,

Frederic