Internet Connection Problems

We have DSL. Starting this week, we are unable to load certain web sites. For example I can look at msn home but I cannot sign on to my mail. I just get a ‘page cannot be displayed.’ Now, none of my other programs have connectivity at all. I’m able to ping successfully and load some websites. I thought it was only secure servers but I am able to log on to some ss as well. I’ve tried updating MSIE but that is also something I cannot connect to. Thanks!