Hi,I'm form China and I'm using a VPN software called XX-NET(this is the link of this project on github : https://github.com/XX-net/XX-Net), and I imported a certificate from this software(the path is /XX-Net/data/gae_proxy/CA.crt). But it didn't work and always show me a page saying your connection is not secure. The weird thing is, when I try to reinstall firefox, the problem remains but the certificate is not in the certificate manager. And when I try to login the firefox sync account, it also says that your connection is not secure. I've tried to delete the Mozilla folder under both the Local and Roaming under my users folder, and even tried to install a portable version, but it's always the same problem. I tried to use VmWare Workstation to simulate another Windows OS, both firefox, the VPN software and the certificate work out fine.So, it seems there is some other information in my PC and I have no idea how to delete it. The same situation happens when I try to reinstall an add-on, the previous settings are not changed at all. Hope you can understand my English and please help me. Thanks. ^ ^.