Security warning

From: Jennifer Shields (jennifershields@hotmail.com)
Date: 04/01/03 

From: "Jennifer Shields" <jennifershields@hotmail.com>
Date: Tue, 1 Apr 2003 13:05:25 -0800

I keep getting this security warning message:
Warning. The authenticity of this content cannot be
verified, therefore it cannot be trusted.

The test root has not been enabled as a trusted root.

Do you want to install Popup killer no more popups....
ZeroPopupkiller.com

I'm going crazy, this message is popping up ALL THE TIME
now. I have even tried downloading the popup killer that
the message is advertising just to see if the message
would stop, but it doesn't. How do I get this to stop?