FreeFixer works by scanning a large number of locations where unwanted software has a known record of appearing or leaving traces. The scan locations include the programs that run on your computer, the programs that starts when you reboot your computer, your browsers plug-ins, your home page setting, etc.
FreeFixer does not know what is unwanted, so it presents the scan result and its up to you decide if some file should be removed and if some settings should restored to their default value. Please be careful! If you delete a legitimate file you may damage your computer.
To assist you when determining if anything should be removed you can find more information at FreeFixers web site for each item in the scan result. You can for example see what other users chose to do in the same situation.
You can also save log file of your scan result and consult the volunteers in one of the FreeFixer helper forums.