the Freeserve software has created a new default dial up connection, and of course Outlook doesn't know anything about it. When you do a send and receive Outlook is looking to the dial up connection that you used before, and it's doing what it was told to do - dialling up using that connection.
Have a look in your dial up networking folder (or Start/connect to/show all connections if you have WinXP) and see which connection is set as default.
Then, in Outlook take a look at the mail account settings. You're looking for an option that allows you to select a connection to us, or to tell Outlook to use any available connection. The reason I'm sounding a tad vague about the settings is that I'm using a beta of the new Outlook 2003, and the settings configuration is not the same as other versions. You don't mention which version you're using, but no doubt someone with an earlier version can confirm the procedure for you. In the meantime have a look around your version for the settings options.