Adware warning...

Hello.

 

Recently, this message has been popping up on certain pages of a particular website I've been visiting:

 

<BR>Warning! Your
computer contains software which may steal credit for the purchases you make
using the links below, leaving us with nothing. <A HREF="scum.cfm"
TARGET="parasite">Get more information</A>.
Your browser appears to have
the "KeenValue/SearchUpgrader" parasite installed. This software can present you
with unwanted advertising and compromise your computer's security, and may
invade your on-line privacy and cause errors and stability problems. It might
have been installed without your knowledge

I've tried Googling it and came up with zip and even tried searching for it on both Norton site and on this forum.

 

Does anyone know what this really is and how I can find out if I have it and/or how to get rid of it?

 

Thanks.