Method 5: FOR nForce users only: Rollback driver changes of the network controller

1. Start -> Windows Update -> View Update History
2. Check to see if there is “Update for NVIDIA nforce networking controller” listed. If so, proceed with the following steps. If not, this solution does not apply to you.
3. Goto device manager (Control Panel -> Device Manager)
4. Goto your nForce networking controller (network adapter)
5. Right click properties -> driver tab -> roll back driver to an earlier version.
6. Reboot twice. Important since it will install a new driver next reboot and needs another reboot.