A. This problem can occur if you use Checkpoint Firewall or VPN software and you delete the registry key for a NIC or make substantial changes to the network on a Windows NT 4.0 server/workstation. To resolve the problem, perform the following steps:

1. Remove CheckPoint Firewall or your VPN software.
2. Copy tcpip.sys from the latest service pack to %systemroot%\system32.
3. If the tcpip.sys file is compressed (tcpip.sy_), use the following command to extract it:
   

   expand c:\winnt\system32\tcpip.sy_ c:\winnt\system32 
   

4. Reboot the PC.
5. Reinstall CheckPoint Firewall or your VPN software.