I set up my new PC 2 days ago running Windows 8.1. I was able to visit all websites, including secure ones, w/no issues via Firefox. Last night, suddenly I was unable to access many secure websites. These include Google (Gmail) & Ilines (email). Here is a copy of the Google error: "mail.google.com uses an invalid security certificate. The certificate is not trusted because the issuer certificate is unknown. (Error code: sec_error_unknown_issuer)" There is no button to bypass, as I have seen in the past. I tried deleting cert8.db which didn't resolve anything. I have also tried adding exceptions which also don't resolve the issue. I searched support & found the link for the MS document (link below) indicating that FF & Windows Family Safety certificates are not playing nice. http://support.microsoft.com/kb/2965142/en-us#appliesto I tried to follow the guide, but when I get to step 6, there is no Microsoft Family Safety Certificate in the Trusted Root Certificates Authorities to export. For reference, I do not specifically have Family Safety enabled & am running my PC as admin, no other users. I personally have no use for this but it is my understanding that it cannot be uninstalled, either. I have spent hours researching & making adjustments to different settings to no avail. It is frustrating enough setting up a new PC & transferring info w/out this extra hassle. Does anyone have any other suggestions? FF is my preferred browser, but if this can't be resolved I will need to use something else so that I can access these important websites.