Ubuntu Security :: Something Is Trnsmitting Packets And Grinding Network To A Halt?

I have a small network with 4 users, a Win2003 server for LAN/security functions, and a Dell Blade server running Ubuntu 8.04.1 which runs as our web server on port 80. I manage the Ubuntu server with Webmin v1.42Yesterday, my users weren't able to access the internet nor were they able to receive mail, etc. and no one could access any of the website hosted on the webserver. However, the internal users could access each other's PCs and internal printers and devices - just nothing outside.

I began to troubleshoot: I could see a lot of activity on the Router/Firewall on the port connected to the Ubuntu server. When I unplugged the server, everyone could immedately connect to the internet. So, the problem was originating with that server.When I logged in to the Ubuntu server using Webmin, I checked System>Running Processes and right at the top of the list was the process:ID Owner CPU Command23184 www-data 98.1% ./s 174.120.164.186 7777When I drilled down on this process it said that the parent process was:/bin/sh -c ./s 174.120.164.186 7777I pressed the Trace Process button and it appears to be sending the following repeatedly:Time System Call Parameters Returnxxxx send 125,0123456789ABCDE,15,0 15So, I manually Killed the process and added a rule to my firewall/router to block an IP range that includes 174:120:164:186

A few hours later the same process stars again in Ubuntu,, effectively plugging up my pipeline to the internet and preventing access to the websites being hosted.It suspect that there is some kind of virus on my Ubuntu machine but have no idea how to locate and destroy it. I am relatively new to the Ubuntu world and would appreciate anyone's help immensely! I just don't know what to do!