Failed TCP/IP Internet Loopback Test Error Code NC315-5W

I have a desktop running with Windows XP and the network adapter is Realtek RTL8139/810x Family Fast Ethernet NIC. From couple of days I noticed some small problems with my network hence thought to run PC Doctor to test the connection. While running the same, test got failed itself with the following error message:

“Failed TCP/IP Internal Loopback Test Error Code NC315-5W
Failed Network Communication Test Error Code NC315-1W”

Can anybody please tell me what does that means and how can I fix it? Many thanks for all your helps.

Just like you it is also very difficult for us to understand what exactly that error means. ANyways, you just try pinging ping 127.0.0.1 and let us know what is the result you getting.

Apart from this i would also like to know whether the Loopback adaptor is installed or not? You can find this by running ping 127.0.0.1 in Command Prompt, this will ping the loopback adapter.