It is a Sub7 trojan. It allows a user to externally connect and perform actions on your computer. Removing the server application from the PC will resolve the problem.
http://en.wikipedia.org/wiki/Sub7
wally please learn the difference between a virus and trojans. A virus spreads and deletes files. Trojans open backdoors to the computer (a server) to allow others to connect. The trojan does no harm nor infects files. There is no need to actually format and reinstall Windows in this case.
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