Companies have sued Gator (now Claria) back in 2002 for displaying ads that covered their sites with competitor sites and won. You can see it here:
http://news.com.com/2100-1023-943515.html?tag=fd_top
http://cyber.law.harvard.edu/people/edelman/gator/
If they could win 4 years ago, there's no reason for similar cases not to be won today.
Missie