The PC Tools File and Registry Cleaner is an advanced tool that allows you to manually remove the traces of malware from your PC.
The important word here is "manually". The program won't scan for suspect files, or report on dubious Registry keys: it's up to you to decide exactly what must be deleted. And so the PC Tools File and Registry Cleaner clearly isn't for beginners, then, but it does still have some useful applications.
Suppose you've just noticed a malware infection, for instance, and tried to launch REGEDIT to investigate - but with no success. Some malware will prevent the Registry editor from loading, but if you launch the File and Registry Cleaner instead you're more likely to be successful.
Or maybe you've already spotted a file or Registry key that you believe is related to malware, but find you can't delete it. Viruses will apply all kinds of sneaky tricks to try and protect their own files and settings, however PC Tools File and Registry Cleaner uses its own kernel driver to bypass these layers, so you should be able to wipe whatever you like.
And similarly, some malware will hide files or Registry keys so they're not visible in REGEDIT, Explorer, or many regular Windows applications. But again, the kernel driver allows PC Tools File and Registry Cleaner to find out what's really present on your PC, helping you to detect and remove even the stealthiest of malware.
The program could prove invaluable, then - but keep in mind that using it also carries considerable risks. Even if you successfully delete something nasty, removing just part of a malware installation could still leave your PC crippled and unable to boot next time. Make sure you have any important data fully backed up before embarking on a File and Registry Cleaner session.