From Mary Landesman,
Getting stubborn adware and spyware off your PC can be frustrating. However, there are steps you can take to make the process easier and more effective. First, make sure you have an up-to-date anti-spyware scanner. Do not rely on your antivirus program to do the job. (See Top Spyware Scanners). Before running a scan, shutdown all open browser windows and applications (including email) and then disconnect your PC from the Internet. If accessible, the easiest thing to do is just remove the phone line or cable connecting the PC to the modem.
Scan, reboot, repeat
Scan the system with the anti-spyware scanner and allow it to remove any adware/spyware it finds. Then reboot the PC, regardless of whether you were prompted to do so by the scanner.
After the reboot, and before reconnecting to the Internet, scan again. If the scanner still reports signs of infestation, allow it to remove any traces and reboot again. After the reboot, scan a third time. If the scanner still reports signs of spyware and adware, or you still feel there are traces not being detected by the scanner, the following tips will help.
Use Safe Mode
Spyware and adware vendors often use resuscitators, files that work to keep the adware/spyware infection active no matter how hard you - or the scanners - try to remove it. Booting into Safe Mode causes allows only the most essential processes to activate. While this won't guarantee all adware/spyware resuscitators will be killed, it does ensure the vast majority will be. (See How to Boot Into Safe Mode). Once in Safe Mode, open your anti-spyware scanner and run a complete scan, allowing it to remove any traces of infection found.
Undo the Damage
After removing the active infection, you'll need to make sure it won't simply reintegrate itself when the system is reconnecting to the Internet.
