One of the computers on my network (XP Media Center 2005) seems to completely congest the network whenever it's connected to it. If I leave it disconnected, the network is fine and web pages load quickly on other computers. If I plug it in (while the computer's on), every computer's connection slows to almost nothing, usually almost completely disconnected from the internet. LAN file transfers still seem to go at normal speed, though. Almost instantly after I disconnect the computer, the rest of the network returns to normal. I ran a bandwidth monitor and it says it's only uploading at around ~4 KB/s average, which would not be causing this problem.
I've tried plugging a different computer into that ethernet cable and that does not cause a problem. I have also tried switching ports around on the router and the problem still persists. I did try plugging the computer directly into the modem (usually it's plugged into the router, and the router is plugged into the modem) and I couldn't tell if the problem persisted.
I have tried terminating every non-windows, non-essential process (leaving only explorer, various svchosts, smss, ctfmon, etc.), which did not work. I also tried stopping every non-essential service, but this did not work either. A few processes refused (or took so long I gave up) to stop, namely Telephony and Remote Access Connection Manager (we are not using dial-up)
I suspect that the problem may be the network interface (currently it's running off the on-board LAN port), but I don't currently have a spare interface card to test this. Anyone have any idea what's going on here? I can run whatever program anyone needs for logs or statistics. Thanks.
UPDATE: Did some more testing; it seems that latency is not affected as i constantly get 55ms pings from google.com even when pages refuse to load. I also tested download speed using this test file: http://download.thinkbroadband.com/100MB.zip . The transfer started around 10KB/s and slowly creeped up to 300KB/s before I killed it (my max download speed is around 1300KB/s). This seems consistent with at least one other person's experience. I also tested DNS resolution, by loading a web page using its domain name, and using its IP address (someone else resolved it for me so it wasn't cached by Windows) and they both loaded at the same speed.
Have you already checked for Malware/Viruses?
I've come across numerous computers infected with one type of Malware or another that exhibit very similar behavior.
Yeah, there was something called Antivir Solution Pro, and I removed it using Malwarebytes, then did a second scan which came up clean. The next day I did another scan and it came up with 3 objects, which I removed; the next scan was clean again. I just did a quick scan just now and it also came up clean. The problem did start happening around the same time as the virus was installed, but as far as I can tell the virus is gone.
What I don't get is that the virus has not affected anything else outside of that computer, because the problem only occurs when that computer is connected to the network. Also, according to two bandwidth monitors, the computer isn't using any significant network resources while it's connected. I'm going to try putting in a NIC in a minute to see if that helps.
UPDATE 2: I added a network card, I still can't get it working fully (DNS doesn't seem to work right), but the problem is still occurring so that did absolutely no good. I'd love to try a Windows repair but I don't have the disks for the OS (Windows XP Media Center Edition Version 2002). I'd do a System Restore, but I'm afraid of that bringing the virus back (would it be safe to restore to a few days before the virus?)
Edited by tony311, 22 July 2010 - 12:13 AM.