That's a search page which link did you use?
Hit same problem earlier in week when downloading a program to backup emails via a Cnet link
it downloaded zonealarm search bar, firewall and hijacked my start page, locked me out of the internet as ZA firewall and my own firewall clashed. I had unticked some other stuff that was also packaged with it but didn't see the ZA stuff to untick - B...dy annoying.
I will avoid cnet downloads in future