So I registered just to toss in my 2 pennies.
I have the exact same problem the OP has.
Working on a computer for a friend, she had a massive 4 Trojan and I suspect rootkit invasion on her laptop that runs 32bit Vista. After slogging through startup, ran malwarebites and removed the malware. I didn't think to run a rootkit scan at the time, stupid me. Computer worked fine after removal. Internet worked, wifi worked, I downloaded and updated the computer using Windows Update. Assuming everything was in order, I gave it back to her.
A few days later, the computer suddenly stopped connecting to the internet via WiFi. She did nothing to the computer since I gave it back to her other then download and install iTunes.
And while I love blaming that piece of bleep software iTunes for everything, I knew that wasn't the case.
So I took it home again, and tried to connect it to my WiFi network, thinking maybe she just got blocked at her work WiFi for downloading iTunes. No dice. It would connect to the network, but local access only and no internet.
Next step was playing around with the network setting to make sure they were all correct. Networking is my weak point, but I got through it and they all appeared correct, or as correct as I was going to get them. I knew at this point it wasn't my WiFi, so no router resets or anything like that were performed because I had 4 other computers and a phone connected to it.
Next came driver reinstall. Nothing. Interesting enough, she's running an Atheros card too.
Out of desperation really, I tried hard plugging the computer directly into the modem. Bingo! Internet!
So I have a network card that would connect to the network but not the internet, but when I hard plugged the computer into the system, it suddenly worked.
Because my network-fu is weak, I decided the next best step would be a reinstall of windows. She didn't have anything on the computer she cared to keep, so gave me the ok to wipe the system. I figured if anything was wrong I was missing, a clean reinstall would fix it.
Unfortunately, she didn't have a disk.
Luckily (or unluckily as it turned to be) the computer came with a system recovery partition. So I ran that, formatted the hard drive and reinstalled Vista and a load of crapware.
Still had the same problem. Could connect to the network, but not the internet.
Understandably, I'm getting a bit frustrated by now. So I slog through windows updates, removing crapware, thinking that perhaps if I have it updated it will magically start working.
The answer is of course, still no, but interestingly enough, I did find a (the?) problem. I ran a rootkit scan and found 4 files. When I tried to fix them, it threw me an error and said: "cannot fix". Great.
It all started when I couldn't get the laptop to install Vista Service Pack 1. It would "download" the update, install, ask me to reboot, I would, then when I went back to updates to check for more, lo and behold, it tells me it needs Service Pack 1 installed. After several attempts at this, using windows update, then manually trying to update it, I finally gave up and went searching for an answer.
Following those links get you here: http://technet.microsoft.com/en-us/library/cc700813.aspx
And then ultimately to the answer here: http://answers.microsoft.com/en-us/windows/forum/windows_other-windows_update/pc-rendered-unusable-after-attempting-to-install/c44429fb-3f7c-4646-8529-5a97bb3cd0eb (scroll down to the answer part of that post).
System recovery didn't work because I believe the rootkit infected the partition. So I'm assuming trying to recover only embedded it further.
Since I don't have a Vista install disk, I'm kind of up a creek with this one right now, because I can't do a clean install. I have Windows 7 on a USB stick, and I think a clean install of 7 will solve the problem but my friend is going to have to buy a key.
Just as a fun aside, the network card does work. I plugged in my Linux Mint 16 USB stick and ran it off the stick without installing it. Computer works fine on linux. The wireless card works just fine, and it connects to the internet as well. In fact, I'm regisering, browsing, and typing this entire long winded response on that linux install that is connected to the internet via the wireless card I thought initially was broken and needed to be replaced.
TL;DR If you ran a system restore, you probably didn't get the entire infection. If you ran a disk that came from the company that sold you the computer (like HP), that isn't a full install of Vista. Only a clean install as listed in the third link has a chance to fix it. I'd wager one of those applies here. Sadly, since I don't have a full Vista install disk or an extra Windows 7 key lying about, I can't test this to see if it indeed works. However, I know the computer works fine if I can get Linux running off a USB stick to connect successfully to the net via the wireless card.
Anyone else have any experience on this? I'm still partially in the dark on it, however I'm thinking (hoping?) I'm beginning to see the light at the end of the tunnel.
Moderator Edit: Split off from another post for clarity
Edited by rotor123, 28 March 2014 - 02:29 PM.