I have a peer-to-peer network with 4 XP machines and 3 WIndows 7 machines.
I have one XP machine that was slow accessing the Internet with both Internet Explorer and Firefox. And we are unable to ping the workstation from other computers.
BitDefender was installed, and its firewall service was on.
It appears the BitDefender found a virus several days ago.
Tested Internet with and without BitDefender firewall enabled - definitely working much better with firewall disabled.
We saw that the profile for the firewall was set up as "Remote", meaning that most services inbound would not work. Changed to "Trusted" settings and tested IE again. Now works same as when it is disabled. Left as disabled for now.
Troubleshooted inbound network communications. Not a duplicate IP issue, ARP table shows proper entries for the workstation. IP address is 192.168.0.245, MAC is 00-1e-4f-d6-90-12.
Attempted to restart Windows Firewall service - cannot start service, missing dependencies.
Reset TCP/IP stack - no change
Uninstall/reinstall network adapter and restart - no change.
Attempt sfc /scannow on PC - receiving error and unable to run, says that RPC connection unavailable.
Uninstalled BitDefender on the chance that it is causing issues. - no change
We installed Microsoft Security Essentials for the time being.
We are still unable to "see" this computer on the network or even ping it. We are able to see it in our modem/router's device table.