Original Poster:

When you say Dual Mode you know that means actually 2G OR 3G connectivity, NOT 3G or WiFi?

Use the Personal IP Address settings desktop widget to confirm that you are receiving an IP address when you handover to cellular connectivity.

It could be that you are not creating a PDP context, and therefore not getting an IP address.

Also, when it happens are you connected with 3G or 2G?