Vista - XP Networking bugged after virus?

This is a bit complicated so I'll do my best to explain. Started a new job and the network setup here was ridiculous. Some computers were on domains others were on a workgroup but somehow all were seeing shares without a problem. All the PC's are XP Home except one which acts a server for a few files which is a Vista Home PC. What confuses me most is somehow the Vista machine is part of the domain which by everything I have read is impossible. When I check the settings it only says in a workgroup of the same name is the domain, but it did show up in the domain.The other day while browsing a webpage (whitepages.com) I got a virus through one of the banner ads. I have cleared the virus out but the pc no longer shows up on the network at all. I can connect to it manually by typing in the IP address into the browser bar and have access to the files but cant find it in the workgroup or domain, I have tried changing it to the same name as the workgroup to no avail. Another problem is I have to set the ip address in the ipv4 setting otherwise it does not set a proper ip address automatically to connect to the internet or the network. I have no idea why its not working I have checked all the settings on all the computers to no avail. Any and all help is greatly appreciated. If you need more info please dont hesitate to ask.

I had a similar experience (minus the crazy network) a few months ago. The first thing a lot of virus' do is change your firewall/AV/internet settings/Proxies. I would check all of these first. Some will block ports on the firewall to let no incoming traffic while others will just hose your whole install. Same goes for the AV on your system (this was my problem, once disabled everything was fine) and lastly check to make sure the virus didn't set up a proxy.

Hope that helps!

i guess i should have mentioned I disabled the firewall and only av on the system is microsoft security essentials.....i have repaired the hosts file and reset ie and firefox proxy settings as they were screwed up.....