RegRun Reanimator is a tool to help you find and remove malware, adware, rootkits and other annoyances that your regular antivirus program may have missed.
Launch the program and it presents you with plenty of options. There are scans to look for browser problems, for instance, or check your Windows startup programs. It can list unidentified files, and check these for malware at VirusTotal.com. And there are modules to back up the Registry and key system files, restore these in the event of any problems, and undo some of the damage caused by malware (disabling Regedit or Task Manager, say).
A not-so-clear interface means accessing all this power isn't as easy to use as it should be. And with the program raising plenty of false positives, too, this isn't a tool for PC beginners.
Still, RegRun Reanimator can help to identify dangers which other software might miss. It's completely free for personal use, and doesn't come bundled with any adware of its own.
There's also a useful bonus feature in RegRun Reanimator's ability to produce a detailed report of your PC's current status, covering your installed programs, browser setup, Explorer extensions, network settings, key file associations, right-click menu options, drivers, Windows service details, codecs, startup programs, scheduled tasks, running processes, loaded DLLs and more. It's great as a record of your system configuration, and can also be very helpful when you want to troubleshoot problems on someone else's PC: just get them to run the program and email you the report.