There are certain viruses that are impossible to detect, no Nortons or Kapersky can detect them. But they are easy to spot, and detect by human eye. For one, they will inhibit any anti-viruses ability to scan almost all files on your computer, this is easy to detect by closely watching your manual scans.
How to confirm you have it, you can't rely on your anti-virus at this point. You have to go into your anti-virus through "My Computer" and find the files that have been changed (This is to determine that you have this type of virus). If you detect any strange icon changes or data type changes, this is indeed a virus.
How to get rid of it, the icon should match the program that has put it on there (This virus typically comes with downloaded software). Find, and incinerate all traces of that software, and if possible, uninstall it as well. If there is no icon change, but only a data type change, then you will either have to manually check for a match to that data type or input that datatype into the anti-virus and manually scan your PC.
One downloadable software I'm aware of that carries this is "Lord Of Chess" a downloadable chess game apparently. So, try to avoid that one.
I cannot fathom that the Lord has blessed us with logic and rationality and have us forgo their use.