Because I'm not having the problem from here and we haven't had any other reports of it, I have to assume for now that the problem is local to your device. First thing I'd try is deleting your browser cache. It does seem unlikely that you'd have a corrupted cache across three browsers, but worth a try. Can you send me a screen capture of the error message via PM?
Could be an issue local to the specific laptop. Since it affects multiple browsers I’d look at the network reset and maybe changing the dns entries as well as turning off browser extensions. Could be a Trojan type extension has been introduced to all browsers - a scan with something like Malware Bytes might identify the issue if that’s the case.
A fairly good link to how to correct some of the potential issues is located here:
Thanks @twalker H260! Great input. This situation turned out to be a VPN running through a data center offshore that we had blocked at the firewall, but I was not aware of this information behind the error. Much appreciated.