You don't say what AV you are using!
Download, install and update Malwarebytes and Spybot Search & destroy.
Scan with them in Safe Mode, as well as with your Anti-Virus.
If you have probs downloading, use Safe Mode with Networking to download,
install and scan..
All info below.
http://www.spybot.info/en/index.html
Spybot Search & Destroy 1.6 is a very good, FREE Anti-Spyware Program.
Download, install, update, and immunize your System with it.
Then SCAN with it.
Update it, and scan your System once a fortnight.
http://www.malwarebytes.org/mbam.php
Malwarebytes is as the name says, a Malware Remover!
For the Free version scroll down their page to either download from
Download.com, or Major Geeks.com
Download, install, and update.
Important re: Safe Mode
If you happen to find a problem that you can’t uninstall / delete, reboot
the computer, and go into Safe Mode.
To get into Safe mode, tap F8 right at Power On / Startup, and use UP arrow
key to get to Safe Mode from list of options, then hit ENTER.
RESCAN your computer with your Anti-Virus, Malwarebytes and Spybot S & D
while in Safe Mode.
If unable to install above Programs in Normal Mode:
Sometimes Trojans, Viruses, Malware, etc stop you installing and/or updating
Programs to remove them.
If that happens, reboot into Safe Mode with Networking, and install, update
and scan from there.