Moved this from Communty Interface Help to SecurityCenter for better support.
Could you please clarify what operating system and service pack (if applicable) plus what version of Internet Explorer is installed (EVEN IF YOU DO NOT USE IE - THIS IS IMPORTANT).
Check Windows Network and/or your Device Manager to see if there are duplicate Internet Connections that may be confusing the software. If so disable any you do not use.
Were you able to access other websites or this happens to McAfee sites alone..?
Try switching browsers such as Google Chrome and Mozilla Firefox - verify if the same issue arises
Try another known Antivirus site can you go to it? Wondering as some malware block you accessing known AV sites . Try scanning your PC with the free Malwarebytes and stinger from here
You may need to download the seetup files for them on anotehr PC and copy to a usb stick. Some times also necessary to rename the files and folder the software needs to be installed into.
Just another thought