Spybot-S&D can also clean usage tracks, an interesting function if you share your computer with other users and don't want them to see what you have been working on.
Spybot-S&D is free, so there's no harm giving it a try to see if something has invaded your computer.
Spy Bot - Search & Destroy is a full featured security solution designed to keep this kind of malware away from you, while also providing a suite of tools for file shredding, managing startup items and generating statistics.
The setup process runs quite smoothly, without taking too much, while the interface has a clean and professional look, with all the available options in the main window.
Spy Bot-S&D allows you to exclude selected cookies, programs or extensions from being reported, allowing you to prevent false positive messages for items that you dont want to be alerted of every time.
It can even scan your download directory for files that have been downloaded, but not yet installed, allowing you to detect unwanted programs before you even install them.