i have the same problem i use spysweeper by webroots and also use mcafee my mcafee doesnt pick anything up but spysweeper picks it up as a high risk adware this is what spysweeper says about it:

Name: WinAd

Unique Code: OO4XS

Type: Adware

Severity: Very High

Description: WinAd is an adware program that may display advertisements on your system.

Characteristics: WinAd may display advertisements on your computer.

Method of Infection: WinAd generally propagates itself using dialog boxes, various social engineering methods, or through scripting errors. Usually adware and BHOs are bundled with various free software programs.