The first thing to obtain via download from the internet is Malwarebytes Malware remover available at
http://www.malwarebytes.org Download the program, install it, upgrade it (for new definitions since its release). You can run this normally, but I recommend that it be run in Safe Mode (press F8 after Power On Self Test). The reason why is because some viruses hide in a part of the hard drive not accessible in the normal user/ admin mode.
Next, one of the many good anti-virus programs is Avast! It can be obtained from:
Here Again, download it, install it, update it, register it (it requires registration for a free one year license) and run it. Again, Safe mode is your friend.
Finally, because not everything catches everything, I would recommend that one go grab a copy of
Spybot Search & Destroy spyware remover Download it, install it, upgrade it and run it.
All of those SHOULD get rid of any nasty bugs that a person may catch. These are not guaranteed, but they are MY choices for virus removal tools.
Also, please note, one may need to boot into safe mode with networking (XP and newer) if the normal log on won't allow you to go to those sites. I'm pretty sure that Malwarebytes & Avast will install in Safe mode. Once installed they will run. A last chance effort may require you to download these programs from a different computer, burn them to CD (or DVD, if that's all you have) and run the install on the affected computer from the cd. You may or may not be able to upgrade them, but at a minimum, run them.