Setup
Before you start removing infections, there's a few precautions you should take.
These steps will help cripple most infections, making them easier to remove.
Restore file associations.
Sometimes infections will remove your ability to directly run programs. This is often done so that while you can use shortcuts to still launch your browser and other programs, you can't run installers or tools to remove the infection. Luckily this is a quick fix.
www.dougknox.com/xp/fileassoc/xp_exe_fix.zip
Download that file and open/run it. You should see something called xp_exe_fix.reg inside. Double-click that, and you should get a confirmation/warning. Click the Yes or Merge button (whatever your system says) to fix the EXE association information. You may need to restart afterwards before programs will run.
Disable Browser Addons
During the removal, you should run your browser with addons disabled so they don't get in the way of removing the infection.
Internet Explorer
In your start menu's programs list, go to Accessories, then System Tools, and then Internet Explorer (No Addons).
Firefox
Hold down the Shift key while starting firefox to go into it's Safe Mode (which has addons disabled).
Chrome
Open chrome normally, then press CTRL+SHIFT+N to open an incognito window, which has addons disabled. Close the original window and use the incognito one.
Disable System Restore
Viruses and other infections can hide in restore points, so we need to clear them.
XP
In your start menu, go to the control panel, and there should be a bunch of icons, one of them being system. If not, click switch to classic view on the left. Open system, and click the system restore tab at the top. In that section, click the checkbox to turn off system restore on all drives, if it not already checked. Save the settings. That will delete any older system restore points, which could easily contain viruses, to prevent them from coming back in the future if you use a restore point.
Vista
Open the start menu, right-click Computer, and click properties. In the new window, go near the top-left and click System protection. In a new window, you'll see a list of your drives. Uncheck them. Tell windows that you want to turn system restore off by clicking the button when it asks you.
Windows 7
Open the start menu, right-click Computer, and click properties. In the new window, go near the top-left and click System . In a new window, you'll see a list of your drives. Below that, click the configure button. In the next new window, choose Turn off system protection, then click the OK button.
Delete the HOSTS file.
The HOSTS file can be used to redirect good addresses (like google.com) to bad ones (like thiswebsiteisavirus.com), so we should delete it to be safe.
In your start/globe menu, go to the Run command. If you're on vista/7, you'd click in it the little white box near the bottom. Copy the below text and paste it in the box, then press enter.
Quote:
%
systemroot
%
\System32\drivers\etc\
In the folder that pops up, there should be a file named hosts with no extension. Delete it.