Combofix is an specialized malware removal tool (for advanced users only) that scans your computer for known malware and, if found, attempts to clean these infections automatically. The program can detect a variety of common malware infections and in many cases clean your computer or otherwise provide you with a log file that a computer technician can use to manually attempt a removal.
Combofix is a quite capable tool if used by an experienced or trained users. In the wrong hands however, it can cause some serious damage and potentially leave your computer unbootable. BEWARE: You should NOT use Combofix for casual malware scanning but ONLY if you know what you're doing or have been instructed by a technical adviser to do so.