Have you told Apache that it should have that IP address?

Do you have a dynamic address?? - Cos Apache by default assumes that it's IP address is 127.0.0.1

Check the httpd.conf file, normally it will say something about "assuming ServerName 127.0.0.1"

If you have a hostname, you can use:
ServerName dhcp19.wdf.intercomponentware.com

Else, I assume you will have to change it every time you dial-up =)

Hope thats got it...