HijackThis

HijackThis is a free system tweaking utility that is very useful in the removal of various pests, particularly of the adware/spyware/browser hijacking variety.  However, it has no automated detection or removal capabilities and requires expert knowledge to be used effectively (and safely.)  It is recommended that the program be used only under expert guidance.  The current version, which now belongs to TrendMicro, can be downloaded by clicking here.