ebates

Hi
i have recently been having trouble with cash back webstes like "Ebates" or shopathome.com where you click a merchant link and it leads to that store. When i click the link it goes to a 404 page not found. Even other sites like slickdeals.net.. when i click a link to go to lik newegg for example it leads to a page not found. someone told me it had to do with my hosts file
how do i know whats wrong?
because some merchant files work, its jus some other ones that dont
and my friend did it on his mac and he is having the same issue but
ebates said there is nothing wrong with their website

thanks a lot!
Romy
im running malware removal at the moment