I would like to suggest running Malwarebytes but as you are unable to access this website we need to fix that first.
As you didn't say which browser you are using I'm going to assume its Internet Explorer. So, go into the settings, then the connections tab, then look in LAN settings. Usually malware sets up a "localhost" proxy which monitors and blocks antimalware sites. If you see a localhost setting, please disable it and try the website again.
Let me know how you get on.
RisingUK PC Security @ Rising-UK.com