Getting "Web Attack: Malicious Cookie Activity" Only when coming from Google and in IE8

Hi.

 

We're getting a  "Web Attack: Malicious Cookie Activity" message when we are trying to access our website Http://www.barrierfreehomeplans.com

 

It only happens when coming FROM GOOGLE. Not when typing the address directly.

 

Also, it only happens in IE8 (as far as we're concerned)

 

Why is this happening? What line of code is triggering this? How can I change it? Fix it? Thanks.