I now have three users with similar troubles regarding making a successful dial-up connection with their Latitude D600/D610 (WinXP-SP2) notebooks.
After booting or standy/hibernate... the users attempt to connect to their ISP.  The connection is successful, IP addresses and DNS servers are assigned, yet they cannot access the Internet. 
If they then disconnect and redial, the connection again gets established correctly, but this time they can access Internet resources.
Any insights or suggestions that would address this behavior? 
Renewing the IP address either before or after the initial connection has no effect accessing the WWW.  This nuisance is consistent across different ISPs and the same dial-up number to the same ISP. 
thank you in advance,