@pjk
Thanks for your patience and suggestion.
I followed your steps and their is a "unlock" button in the CHM files property dialog. By the way, this is the first time I saw such a button
.
I'm wondering how to set my IE back to original setting. I just press the button "Internet option -> security -> reset all zones to default level". (By the way, I seldom use IE, most time, I use Firefox,
).
Thanks again!