Losing Internet Connection

Somebody help me please.. If I connect a certain PC onto the network, everybody else on the same network will lose internet connect. What kind of spyware should I be looking for with this problem? I ran Kaspersky Antivirus but didn’t find anything on the certain PC.
The problem is fixed if I disconnect the certain PC and restart the T1 Modem.
Appreciate any advice.
Answer #1
Place your Internet Config here by running this command in DOS! or Command Prompt
ipconfig /all