Combofix is a freeware utility that scans your PC deeply for spyware and malware, especially in combinations. It's a powerful tool that can remove stubborn infections but also delete files you need, if you let it, so inexperienced users who run Combofix without expert guidance do so at their own risk. Used properly, it can clean your PC much more deeply than typical tools, free or not, and not just of malware but other junk, too. It finishes with a detailed log that reports each step.
Combofix is portable freeware that runs when you click its extracted program file. We disabled our antivirus and firewall software, as Combofix recommends. Most programs advise you to close everything before you install them, but Combofix means it, and it'll tell you if an open window or running process needs to end before it can proceed. The program also automatically backs up your settings and creates a System Restore point, which is reassuring.
Combofix is mostly automatic in operation. It scanned our system and started deleting files at a rapid pace. A look at the scrolling log reassured us: Combofix was throwing out hundreds of tiny JPEGs left over from an uninstalled app. Other cleaners (which shall remain nameless) had missed them, and we were pleased to see them go. Most scans take less than 10 minutes, but infected PCs may take much longer; ours was clean, thankfully. Finishing requires a reboot. Things seemed to load and run faster; an extra benefit of this deep cleaner.