When using a Windows XP as guest operating system in Virtual PC 2007 with Shared Networking or NAT (Network Address Translation) as network adapter, the system cannot connect to Internet and unable to browse the websites with any web browser, including Internet Explorer and Firefox.

The unable connect to Internet from Windows XP virtual machine in VPC happens without reason, and despite the networking via NAT works before the problem occurs. Beside, any connection using protocols that do not require domain name translation works. For example, FTP, secure FTP, telnet or SSH to remote server on Internet by using IP address instead of host name.

The problem happens in Windows XP guest operating system because of incorrect DNS server been assigned automatically. The error may arises from user has manually set the wrong IP address for the DNS server. In this case, verify that the DNS server can indeed resolve a domain name or URL correctly (i.e. ping a valid domain should at least return an IP address), and set the DNS Server address in Windows XP guest OS in virtual machine according to what is in used in host operating system that runs the Virtual PC.

Another possible cause is incorrect assignment by VPC virtual networking adapter. By default, Virtual PC virtual NAT router will allocate and assign to guest operating system the same DNS server that’s been used by host operating system if the network connection properties for TCP/IP protocol is set to obtain DNS server address automatically. However, for some reason, the DNS server used may be incorrect or invalid, such as when in the cause that user switch or change Internet connection used which has different DNS server, or change to new DNS servers without restarting the host computer.

In this kind of symptom, close the virtual machines and then exit and restart Microsoft Virtual PC Console. The problem should be fixed after that. If for any reason you can’t shutdown the guest operating system, just simply manually configure and set a fixed DNS Server IP address in the Internet Protocol (TCP/IP) Properties for the Local Area Network (LAN) Connections (may be in another name).

Note that if you’re installing Windows Vista, Windows Server 2003 or 2008 as guest operating system in VPC’s virtual machine, there is another DNS Server issue that cause unable to connect and browse the Internet problem, where resolution requires a manual set the DNS Server IP address to