solution
Saeed17,
Today I had the exact same problem as you did (after a reinstall in my case). I googled it, that's how I ended up here. Unfortunately there was no solution here (though Gars did send you in the right direction. Wish I read his comment in the beginning, it would have been helpfull... I skipped it when I was reading this forum and only saw it just now comming back to write the solution for you)
But the good news is I did finally solve the problem. The solution works as follows:
The ethernet adapter is NOT a seperate device. It is integrated on the motherboard. So dont go looking for a driver for the network adapter, you need to install the driver for the
motherboards chipset. Finding that out was the key. From there on it was downhill (sort of) I have a HP Pavillion (as do you I read) with a Nvidia nFORCE 220 chipset. You probably have the same since de ethernet device is listed as "nVIDIA nForce MCP Networking Adapter PCI". You had more to go on by the way, for some reason my system only said "10/100 BT networking device". Which narrows it down to about 10 million devices
If you are not sure which motherboard (and thus chipset) you must go here, like I did:
http://welcome.hp.com/country/us/en/support.html?pageDisplay=support
Enter the product name of you PC (It probably shows on the front of your pc). In my case it is Pavilion t160.nl. In the following screen you click on "product information" there it says everything you want to know about you hardware.
When you found out what chipset you have, you go to:
http://www.nvidia.com/content/drivers/drivers.asp and click on "platform/nforce drivers". Like I said I have the nforce 220 chipset. So that's what I was looking for. I dont really like nvidia's site, it seems to be made by and for computer wizzards, not end users. The nforce 220 isn't listed anywhere (also couldnt find drivers for it using google). In an article on some other site I had to find out that nvidia makes a so called "Unified Driver Package" that includes drivers for a whole range of models such as the nFORCE 220/230/415/420/430 and more. Even after knowing this nvidia's site still doesn't make a whole lot of sense to me (you will know what I'm talking about when you see it, it gives the impression to only list recent models but i'm not sure about that... and I dont care actually) but I knew enough by then to make an educated guess and selected nforce 1/2, then selected my OS and downloaded it.
This was on another computer ofcource since I use a router and I had no network connection. After transfering and installing the nvidia driver package the ethernet adapter (and some other devices ofcourse) worked better then ever before. I'm not sure all my devices work yet, I see some questionmarks in the windows device management list. But thats not a problem for today. First some sleep
Hope this solves your problem as well. I think so.
This was the last nerdy s**t I'm doing for the next 20 years.
Later!
Don
PS I have no idea how the avarage pc user could have figured this out. So shame on you HP and NVIDIA! Things should have been A LOT more user-friendly by now. This area has hardly improved since my techy days in the 90-ies. This su**s. I'm not touching my PC for the next 10 years. I'll wait for the moment when my PC works as end-user friendly as the TV in my livingroom. By then I'll concider doing more than just opening MS Word and sending an e-mail.