These few days the internet connection of my laptop is a little bit weird, and I am doing the trouble shooting right now.
I found that I couldn’t open up the main panel of Comodo firewall, and this never happens before.
(However, It seems that the firewall is still working.)
The problem is still there even after I reinstalled the Firewall. Could anyone help me solve this plz?
Okay now it’s getting worse, the Firewall is not only outta control, it also blocks the connection to internet, so I’ve got no choice but to uninstall it temperately. I’ve been using this firewall for many years, I hope I won’t need to find another one for being unable to solve this problem. 
Thanks airatgab! I will try again and see if this works. :-TU