• Try using a different cable that you know works. If using a permanently installed cable, plug another computer that you know works into it and use different patch cables.
• Make sure that you have the proper driver installed on the computer.
• Check to see that all of the other software components required for network communications, such as clients and protocols, are properly installed on the computer. If no problem is found with the driver, the cable, or the network configuration parameters, then it is time to start checking NIC. Before you open the computer case, check to see if the NIC manufacturer has provided its own diagnostic software. If you are using a Plug and Play, you might not have even looked at the disk included with the NIC, but this is a time when it can be worth your while to do so. If the card is functioning properly, and assuming that the software providing the upper layer protocols is correctly installed and configured, the problem is probably caused by the hardware resource configuration.
There is a resource conflict between the network interface adapter and another device in the computer, or the network interface adapter is not configured to use the same resources as the network interface adapter driver.
Use the configuration utility supplied with the adapter to see what resources the network interface adapter is physically configured to use. You may have to adjust the settings of the card or the driver, or even those of another device in the computer, to accommodate the card. If the NIC is malfunctioning, due to a static discharge or a manufacturer’s defect there is not much you can do except replace it. Before you do this, you should check to see that the NIC is fully seated in the slot, as this is a prime cause of communication problems. If the card is not secured with a screw, press it down firmly into the slot at both ends and secure it. If the problem prolongs, try removing the card from the slot, cleaning out the slot with a can of compressed air, and installing the card again. If not, you can try using another slot. After exhausting all of these avenues, trying installing a different card in the computer, either a new one or one from another computer that you know is working properly.