Network Card added to Server

Hi,
I have a H.P. Lh4 Server connected to a windows nt4.0 network. It’s a stand alone Server. I recently installed a second network adapter card. Configured it W/ a static ip address. Creating a private network keeping it off the main network.
When I rebooted the system it no was no longer on the network. When I would delete the driver for the new card it was back on the network. I tried switching the pci slots that the new card was installed on w/the same results…Why would the installation of the new card take the computer off the network when the original card was never touched…Any help would be appreciated..