|It could be the TCP/IP stack but then again it could be your router. We will start by thinking the problem is in your computer. Try going into the properties of your NIC then remove the TCP/IP protocol and re-adding it. Before you do this make sure you have drivers for the NIC standing by because you may have to uninstall the driver and reinstall it.|
If this does not work then I would look at the router as having problems and trouble shoot from there. You could always buy a new NIC and see if it make a difference because they are only like $15. If you had another NIC then you could do a loop back test to verify the problem is not in your computer.
If you hooked a Cross over cabel between the two NICs and got an APIPA address assigned to your IPCONFIG then you would know there is not problems in your computer. If you had a second computer then you could simply hook up a cross-oever between them and see if you can talk to the second computer.
But really, I think the problem is either in your driver or the registry because the virus may have messed with it.