I installed the add-on Stleathy-pro (on official Mozilla add-on site) and now I can't get access to the internet via Firefox. I get the message: authentication required. The proxy moz-proxy://proxyuk.stealthy.co:3128 is requesting a username and password. The site says: "Please provide your credentials for Stealthy PRO. (image attached) The access with other software is random, and now I have lost access to some file. I think it is a virus. Any idea?