Unable to Explore outside LAN

We recently enabled RAS on SBS 4.5 Back Office. When I use dialup to the server all is fine,(a little slow), when I call my ISP trying to access the web, interaction with the ISP is fine (email, ads & promos) but I cannot open web pages. Unable to use dialup to Compuserve or AOL. Checked & re-installed software and setup for DUN seems OK.
mrobbins@trminc.net