One Vista PC in our small office fails to initialize networking about 1 reboot in 3. Vista's diagnostics are never able to repair the issue. However, the problem can be consistently resolved (until the next reboot) by disabling and then enabling the network adapter in Device Manager.
This is a wired connection to a router. The network adapter is the onboard NVIDIA nForce 10/100 Mbps Ethernet with the current drivers available from Windows Update, and is the only network adapter in the system.
Has anyone seen this issue and hopefully know how to resolve it?
I have seen this issue with the nForce NIC drivers. Symptoms are as you describe: the NIC is not initialized properly on boot.
On a 32-bit Vista Business system with the nForce gigabit NIC, I could only get reliable operation by using Vista's in-box drivers. None of nVidia's subsequent driver updates would work. In the end, I installed all the nForce drivers except the NIC and let my system use the in-box NIC driver.
Try rolling back to the previous drivers.
One other thing: Driver updates on Windows Update cause more problems than any other updates I know. I'm not sure why this is, but I never, ever, install drivers from WU.