Problem with the computer of my boss

We bought our computer at the same time, the only difference is that my computer have a little bit more ram memory cause I compile with it a lot.

It's started to have problems with internet, the green lights in the back were always flashing etc... and a lot of packets were sent. So I tought it was a problem with the network card, we sent the computer back to the store, they cleaned up and said it was a virus. And then it's worked kinda good, but sometimes our internet connection and work-group (peer to peer) is also slow. Today, nothing was working on his computer, closing all the windows etc... Mcafee wasn't able to run, not even to install or uninstall.
And the Window Task Manager was closing .5seconds after I pressed ctrl+alt+delete. So I was able to download on my computer the important files. I scanned them also to be sure there was no virus.

Then we format the computer, all the computer and slowly (not in rapid mode to save time, I wanted to erase every everything). Then everything was going fine, I was able to access to the local network perfectly and really fast between the computers we have here. Then we installed the internet on it, and everything went slow. I status on his internet connection said after 3 minutes that he have sent 16 millions of bytes, and at the same time my computer sent only 134 thousand of bytes. So there is something wrong.
I doubt it can be a virus, onless it always get infected the same way, and when he connected to the internet he got the virus right away.
I am sure there is something else, but I don't know what !?

What can it be, I never seen that before, may be someone know ?

what is the operating system of his PC? Did you install all the support packs and hot fixes? download and run stinger.exe to scan for viruses, also run like adaware. last resort is to put a sniffer in and capture the data coming from his PC to see what it is.

You posted this thread three times. Although you said yourself in the other threads you weren't sure where it belonged, you still shouldn't really cross-post. If it seems like this is a non-networking problem, I can always move the thread later.

it's using Windows Xp

Last Week, I did all the updates, the critical ones etc.... but today we didn't do it after the format, but the samething happenned.

alot of the new viruses use exploits in microsoft to spread, it is very important to follow the recommended steps for removal. if you scanned a PC for viruses and found lets say korgo you remove it whith the scanner then patch the system most likely the machine got reinfected while patching (this is very common) also if you did not turn of system restore and rebooted the system XP might have just put the virus back on it.

Do the following in the exact order!...

patch the computer fully! update your anti-virus!!! then turn off system restore!!! then run stinger.exe ( http://vil.nai.com/vil/stinger/ ) on the computer if it finds somthing then reboot the computer after it is done, then run your local virus scanner if it finds something then reboot after cleaning (stinger only does 46 viruses). after that run spyware utility of choice (adaware, spysweeper, whatever ) after it is done reboot, then download regvac to clean the registry, reboot the computer. turn system restore back on, you are done!!!

you really thing that's the way of doing it ?

To patch the computer, you need to go on the internet (microsoft update website), and when you connect, you get all the data speading.
My boss thing the problem is that Microsoft is infected with a lot of virus etc.... he believe the Update WebSite get a lot of virus, cause when he start to download the security patch etc... McAfee find a lot of virus, but I don't think that's really the problem. I think it's come somewhere else.

When he isn't connected to the internet, the local communication send low and normal data, but when connected all the connection (internet and local) sends and receive a lot of data, around 1mg in less than a minute.

hehe I have cleaned viruses out of so many networks it aint even funny ( except when they get the bill LOL ), the reason you get mcafee finding viruses during the windows update is that it is writing over infected files and catching them, Im not ganna go into how a real-time scanner works compared to local scans, and no way is microsoft's update server infected with viruses, as well you can download the updates and burn them to a CD and push them out so he doesnt have to even connect to the internet to get them (administrators toolbox).
just do what I said.

The only difference here is that if I was there I would put a sniffer in to see what virus I was dealing with and how many computers on the network are infected.