You often have to take a multi-pronged approach to eradicate all the malware. One product usually doesn't do it alone.
First download the following (if the virus is blocking your internet, you may have to download these on another machine and burn to CD or copy to a USB memory stick)
Malwarebytes: http://www.malwarebytes.org/mbam.php
Superantispyware: http://www.superantispyware.com/superantispywarefreevspro.html
CCleaner (cleans out caches) http://www.ccleaner.com
Avast! 4 Home: http://www.avast.com/eng/download-avast-home.html
Now, start the machine in Safe Mode (hit the F8 function key as the machine boots up, and choose Safe mode)
Turn off System Restore on your machine, but only until you get this fixed - many of these trojans get copied into the System Restore files, which anti-virus programs aren't allowed to touch and the viruses could reinstall themselves from there. My Computer > Properties > System Restore.
Then run CCleaner (it'll make scanning faster because it will delete a bunch of temp files and save you from having to scan those.)
Then run Malwarebytes, and clean everything it says.
Then install and run Avast - tell Avast to do a boot-scan - click on "schedule boot-scan" - and restart the computer
Let it start and do the Avast boot scan
Then install and run Superantispyware
Then turn System Restore back on.
Now install the antivirus program and antispyware program of your choice to do continuous scanning, and make sure you keep it up to date.
Always keep your Windows, web browser and Java software up to date - frequent patches are released to plug security holes.
http://www.pcworld.com/article/149298/10_quick_fixes_for_the_worst_security_nightmares.html