How to get rid of this computer virus?

I have a toshiba and I have been running Windows Vista. I recently got a virus that said Vista Antispyware 2012. I couldn't click anything. There was an option to enter in a registry code that I had found online to get rid of the popups. Now, I downloaded Malwarebytyes to try and get rid of the problem but everytimer I run it it say that there was an error in updating the software. I can't run Malwarebytes because it freezes up on me. Somebody please help me out, with as much detail as possible. Thanks