When I try to open certain pages in Safari on a MAC, it instantly gives me the "Safari can’t find the server" message. When I try to open the same page in Firefox on the same machine, it opens normally.  The page that I try to open is "https://..."  Here is the error:

Safari can’t find the server.
Safari can’t open the page “https://en-us/Error.aspx?aspxerrorpath=%2f242686%2fen%2fSignin.aspx%3fReturnUrl%3d%252f242686%252fen%252f%252f242686%252fen-us%252fCheckout.aspx” because it can’t find the server “en-us”.

Please advice.  Thanks!