rachel, if you run a firewall, tell it it to block generic hosts from doing anything. i used to get that issue and i just block generic hosts from trying to access anything on the internet.
on the off chance you are infected with a trojan of some sort, ive found regrun is an amazing program to run checks with and clear weird things from your pc with. its got a 30 day free evaulation period during which time its completely functional. i was so impressed with it i ended up buying a licence
download link --
http://www.greatis.com/security/download.htm