"connection failed" could be due to any number of problems. Try to isolate the situation.
1) Can you access the internet using your normal browser? If not then your internet connection or service provider may be not working.2) Can you access the Interactive Data web site? If not then IDC's server may be down.
3) Have you accessed IDC before from this computer? If not then the instalation may not be setup correctly.
4) Have you installed any other new software since you accessed IDC successfully? If so them you may want to reinstall Navigator Access.
Otherwise, contact IDC customer service to have them check the status of your connection.