I am Not a Geek has posted a removal guide for Gain/Gator/Claria

By far the widest spread form of adware. Claria is known by a number of names such as GAIN and Gator. Claria is the latest name change for a company that is very widely hated (all adware, spyware and malware companies are hated). Tons of "Free programs" install some variant of this ad serving software on your system to make that developer money. This approach to offering free software is NOT something that I currently or ever will approve of.

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