The network adapter on the host computer loses connectivity when you start a virtual machine in Virtual PC 2004 (834310)

SYMPTOMS

When you configure your virtual machine network settings with the Virtual Machine Network Services driver, and then start the virtual machine, the physical computer loses network connectivity, and you may receive the following error message on the virtual machine:

Virtual PC could not open its emulated Ethernet switch driver. Virtual switch networking will be disabled. To fix this problem, re-enable the Virtual PC Emulated Ethernet Switch service or reinstall Virtual PC.

CAUSE

This issue may occur if the Virtual Machine Network Services driver is missing, corrupted, or disabled, or if the associated registry keys are corrupted or missing.

RESOLUTION

To resolve this issue, re-install the Virtual Machine Network Services driver on the physical computer. To do so, follow these steps:

Close Virtual PC if it is running.
Open Control Panel, and then double-click Network Connections.
Right-click the network connection, click Properties, and then click Install.
Click Service, and then click Add.
Click Have Disk, and then click Browse.
Locate the C:\Program Files\Microsoft Virtual PC\Utility\VMNetSrv folder, click the VMNetSrv.inf file, and then click Open.
Click OK.
Restart the computer.

WORKAROUND

To work around this issue and restore network connectivity on the physical computer, remove the Virtual Machine Network Services driver from the network adapter on the physical computer.

Note This workaround only restores network connectivity on the physical computer and does not restore network connectivity on the virtual machine.

To remove the Virtual Machine Network Services driver from the network adapter on the physical computer, open the properties of the network connection on the physical computer, click Virtual Machine Network Services, click Uninstall, and then click Yes.