Hijack This shouldn't be the first thing you do. Did you even run one anti-malware
scan?
Check Add/Remove for anything suspect, you don't recognize as having installed yourself.
Uninstall if possible. Download, install and update MalwareBytes' anti-malware...
run a scan..
Malwarebytes' Anti-Malware
If necessary, you'll need to get further help on a malware support forum. Follow
preliminary cleaning steps on one of these forums. Register and post on only ONE
forum.
MalwareBytes' malware removal forum
GeeksToGo forum
WhatTheTech forumBlocking Unwanted Parasites with a Hosts File