Safari unable to establish a secure coection to the server "authentication.pmi.org"

I am using a MacBook Air ruing OS X version 10.7.5. Safari can open the website www.pmi.org however when I click 'log in' on this website it fails to open the page and the following message appears:

Safari can't open the page "https://authentocation.pmi.org/Default.aspx? r=www.pmi.org%2fdefault.aspx&s=False" because Safari can't establish a secure coection to the server "authentication.pmi.org"

Any ideas on how to resolve the coection issue?