I have an issue that's been beating me up for a week or so. I have an XP PC that will just drop off the network.

What happens is that everything will be fine and then all of a sudden, I cannot browse the internet or use the network at all (shared drives, etc). I can go to a command prompt and ping and get replies, and I can also ping said PC from another and get replies. It's not DNS related because I can ping by name and it will resolve to IP, plus I cannot browse to an IP or access a shared drive by IP of the host.

It's not a network device because other devices are not affected and can continue normally. It's isolated to this one PC. And if I reboot, everything will be just fine... for an undetermined amount of time, then it starts over again.

XP Service pack 3, Windows firewall on, AVG Antivirus (not the internet security package).

I have tried turning Windows firewall off, reseting winsock, resetting TCP/IP, winsock2, everything.
Have ran a spyware and virus scan only to find nothing.

What's even weirder is that if I have an RDP session open to said PC, and it decides to flake, the RDP session will stay up. However, if I close it, I won't be able to establish another session until PC is rebooted.

Any ideas or suggestions?

Try uninstalling/reinstalling the drivers for the network card. Do a reboot after you uninstall them.

Also if you have an extra NIC laying around you could install it, disable the other adapter and see if the problem persists.

I get the same results with a different NIC...