Bit Defender

• The big "Get Started" button on the first page of the website will let you fire up the program. You'll need to access this page in Internet Explorer because that is the browser the site uses. So if you can't use Internet Explorer for some reason, then you may want to try a different website. You have to agree to the terms and conditions by clicking on the appropriate box, and then hit the "Start" button. The program will want to install some add-ons to Internet Explorer, but then you'll be able to get right into scanning. There is nothing to update, since the website is always updated with new virus definitions.
  
  

Eset

• Eset is another free scanner in which you'll need Internet Explorer. You'll also need administrator rights to the machine you're on, which means it probably won't work if you're on a lab computer. There's a license agreement to accept here, too, and it is very much the same in set up as Bit Defender. However, it's always a good idea to try a few different scanners since they are inevitably good at finding different kinds of viruses.
  
  

Being Cautious

• Don't fall for antivirus baiting scams. Basically, these scams will offer a free virus scan on your computer, but will then ask you to actually purchase something in order to rid yourself of the viruses it found. Not only is it not necessary to use an online antivirus scanner that costs money since there are plenty of free ones, these sites will often show viruses on your computer no matter what. In some cases, they may even download dangerous material in order to have something to fix and pull you into the scam. For this reason, it's a good idea to avoid going to websites that you don't completely trust. You should also never click on a link for a virus scanner that automatically pops up on your computer without your telling it to do so. These popups are likely the actual cause of the problem themselves, and so are unlikely to help you fix anything.