I'll take a guess that you are using Microsoft's browser. Try using Netscape and see if that works.

My ISP at home in Pennsylvania is Voicenet and when I'm in Colorado I use Kelly's machine. She has a DSL line and uses Microsoft. I can't access my Voicenet email via Microsoft but Netscape works fine.

I'm not SAYING that Microsoft block competitors' services, I'll leave that for you to decide.