HijackThis

HijackThis, sometimes abbreviated HJT, is freeware spyware-removal tool for Microsoft Windows originally created by Merijn Bellekom, and later sold to Trend Micro. The program is notable for taking a heuristic approach on detecting malware - rather than relying on a database of known spyware it quickly scans a user's computer, creates a list of differences from a known spyware-free environment and allows the user to decide what from the list needs to be removed.