Fc.exe could be legitimate Windows OS process. Fc.exe is a command line entry to compare 2 files or sets of files and display the differences. Fc.exe is an application Fast Cache by Analog X that is a caching Domain Name Server (DNS) that runs on you local machine. (Compared to going to an external source to translate your web request from its name to its Internet Protocol (IP) address.) CAUTION: Various trojan/worm/spyware overwrite or create a file by this name.