Question : Why do I have high ping and a slow Internet connection on a DSL line?

My problem is that I have a slow Internet connection and high ping times on a business DSL Iine.  I have found the source of the problem, but I am having trouble correcting the issue.  The source of the problem is a computer that had a virus on it.  The virus was removed along with any registry entries.  When I ping any website with a TTL of 125, my ping times range from 400+ along with Request Timed Out meassages. Internal network ping times are <1 ms.  If I pull this specific computer off of the network, everything runs smoothly and the Internet is fast on all of the other computers.  The computers hardware has a AMD Athlong 64 X2 CPU, nVidia nForce network controller, and 1 GB of RAM.  I don't see any strange process logs running, but if a HiJackThis log is needed to solve the issue, I can post one.  Thanks in advance.

Answer : Why do I have high ping and a slow Internet connection on a DSL line?

There is obviously some remnant of that virus or Trojan still on that machine. It must be generating network traffic, or it wouldn't have that effect.  IMO, your time would be better spent (more profitably and with more satisfactory results) in wiping and rebuilding that computer rather than trying to find and fix whatever traces are left on that machine.