If you have the original media that came with the system or should have been burned to disc or made into bootable thumb drives, I would rebuild it from the media back to clean out of box state from factory. Virus's like to block you from access to websites/tools that would remove them. Booting from CD, DVD, or thumb drive and setting it back to factory would fix this.
If you dont have the media for this system then let us know and a moderator will redirect this to the Virus/Malware forum where it would get more attention from certified malware specialists. I havent gotten certified yet, so I cant post there, but there are many guru's here who can assist.