Version 5.xx through 6.xx of Internet Explorer will sometimes change from using your default dialup connection to "never dial a connection". This will show you how to reset Internet Explorer.
Open Internet Explorer (the blue "e"). You will probably get a notice screen that says it cannot display the current page, ignore it for now. At the top of Internet Explorer is an option called "Tools", click this and then click on "Internet Options". You'll now have a window in front of you with binding tabs across the top, click on the one called "Connections". On this screen, look directly underneath the white rectangular window in the middle part of the screen. You will see three options, make sure the black dot is in the option called "Always dial my default connection" - after doing so, click "Apply" at the bottom of the screen, then click on "Ok". Close Internet Explorer and re-open it - it should now bring the dialup window back so you can connect and then load web pages after you are connected.